Bump version in README.md.

NOTE: changed versioning system slightly.

.gitignore

@@ -4,5 +4,5 @@ tags
 *.out
 .cache
 build/*
-compile_commands.json
 vgcore.*
+compile_commands.json

Makefile

@@ -1,32 +1,4 @@
-NAME = scl
-
-TARGET = $(NAME).out
-
-SRC_DIR = src
-INC_DIR = $(SRC_DIR)/include
-BUILD_DIR = build
-OBJ_DIR = $(BUILD_DIR)/obj
-GRAM_DIR = $(BUILD_DIR)/grammars
-TEST_DIR = test
-TEST_BUILD_DIR = $(BUILD_DIR)/test
-TEST_OBJ_DIR = $(TEST_BUILD_DIR)/obj
-
-CC = clang
-LINK = clang
-CFLAGS = -Wall -DDBG -ggdb
-LDFLAGS = -lm
-
-SRC_FILES = $(wildcard $(SRC_DIR)/*.c)
-OBJ_FILES = $(patsubst $(SRC_DIR)/%.c, $(OBJ_DIR)/%.o, $(SRC_FILES))
-OBJ_FILES_NOMAIN = $(filter-out $(OBJ_DIR)/main.o, $(OBJ_FILES)) # Object files without main.c.
-GRAM_FILES = $(GRAM_DIR)/grammar.tab.c $(GRAM_DIR)/grammar.tab.h
-UNITY_C = $(TEST_DIR)/unity/unity.c
-TEST_SRC_FILES = $(wildcard $(TEST_DIR)/*.c)
-TEST_OBJ_FILES = $(patsubst $(TEST_DIR)/%.c, $(TEST_OBJ_DIR)/%.o, $(TEST_SRC_FILES))
-
-RESETCOLOR = \033[0m
-WHITE = $(RESETCOLOR)\033[37m
-WHITE_BOLD = $(RESETCOLOR)\033[37;1m
+include config.mk
 
 all: $(TARGET)
 
@@ -34,51 +6,72 @@ release: clean
 release: CFLAGS = -Wall -O2
 release: $(TARGET)
 
+# Run the target.
 run: $(TARGET)
-	@ echo -e "$(WHITE_BOLD)Running... $(RESETCOLOR)./$(TARGET)"
-	@ ./$(TARGET)
+	./$(TARGET)
 
 # Generate grammars with bison.
 $(GRAM_FILES): $(SRC_DIR)/grammar.y
 	@ mkdir -p $(GRAM_DIR)
-	@ echo -e "$(WHITE_BOLD)Generating grammars...$(RESETCOLOR) bison $< -o$(GRAM_DIR)/grammar.tab.c -H$(GRAM_DIR)/grammar.tab.h"
-	@ bison $< -o$(GRAM_DIR)/grammar.tab.c -H$(GRAM_DIR)/grammar.tab.h
+	@ $(PRINT) "$(WHITE_BOLD)Generating grammars...$(RESETCOLOR)"
+	$(BISON) $< -o$(GRAM_DIR)/grammar.tab.c -H$(GRAM_DIR)/grammar.tab.h
 
 # Compile grammars.
 $(OBJ_DIR)/grammar.o: $(GRAM_DIR)/grammar.tab.c $(GRAM_DIR)/grammar.tab.h $(OBJ_DIR)/lexer.o
+	@ $(PRINT) "$(WHITE_BOLD)Compiling grammars...$(RESETCOLOR)"
 	$(CC) $(CFLAGS) -c $< -o $@
 
 # Lexer depends on grammars.
 $(OBJ_DIR)/lexer.o: $(SRC_DIR)/lexer.c $(GRAM_FILES)
 	@ mkdir -p $(OBJ_DIR)
+	@ $(PRINT) "$(WHITE_BOLD)Compiling source object $(WHITE)$@$(WHITE_BOLD)... $(RESETCOLOR)"
 	$(CC) $(CFLAGS) -c $< -o $@
 
-# Compile project sources.
+# Compile project source objects.
 $(OBJ_DIR)/%.o: $(SRC_DIR)/%.c $(INC_DIR)/%.h
 	@ mkdir -p $(OBJ_DIR)
-	@ echo -e "$(WHITE_BOLD)Compiling $(WHITE)$<$(WHITE_BOLD)... $(RESETCOLOR)$(CC) $(CFLAGS) -c $< -o $@"
-	@ $(CC) $(CFLAGS) -c $< -o $@
+	@ $(PRINT) "$(WHITE_BOLD)Compiling source object $(WHITE)$@$(WHITE_BOLD)... $(RESETCOLOR)"
+	$(CC) $(CFLAGS) -c $< -o $@
 
 # Link to final binary.
 $(TARGET): $(OBJ_DIR)/grammar.o $(OBJ_FILES)
-	@ echo -e "$(WHITE_BOLD)Linking $(WHITE)$(TARGET)$(WHITE_BOLD)...$(RESETCOLOR) $(CC) -o $(TARGET) $(OBJ_FILES) $(LDFLAGS)"
-	@ $(LINK) -o $(TARGET) $(OBJ_FILES) $(OBJ_DIR)/grammar.o $(LDFLAGS)
+	@ $(PRINT) "$(WHITE_BOLD)Linking $(WHITE)$@$(WHITE_BOLD)...$(RESETCOLOR)"
+	$(LINK) -o $(TARGET) $(OBJ_FILES) $(OBJ_DIR)/grammar.o $(LDFLAGS)
 
-# Compile test sources.
-$(TEST_OBJ_DIR)/%.o: $(TEST_DIR)/%.c
+# Compile Unity object.
+$(UNITY_OBJ): $(UNITY_C) $(UNITY_H)
+	@ $(PRINT) "$(WHITE_BOLD)Compiling Unity...$(RESETCOLOR)"
+	$(CC) $(CFLAGS) -D UNITY_OUTPUT_COLOR -c $< -o $@
+
+# Compile test object.
+$(TEST_OBJ_DIR)/test_%.o: $(TEST_DIR)/test_%.c
 	@ mkdir -p $(TEST_OBJ_DIR)
-	@ echo -e "$(WHITE_BOLD)Compiling Test $(WHITE)$<$(WHITE_BOLD)... $(WHITE)$(CC) $(CFLAGS) -I$(SRC_DIR)/include -c $< -o $@$(RESETCOLOR)"
-	@ $(CC) $(CFLAGS) -I$(SRC_DIR)/include -c $< -o $@
+	@ $(PRINT) "$(WHITE_BOLD)Compiling test object $(WHITE)$@$(WHITE_BOLD)...$(RESETCOLOR)"
+	$(CC) $(CFLAGS) -c $< -o $@
 
-# Link the test executable.
-test: $(TEST_OBJ_FILES) $(OBJ_FILES_NOMAIN) $(UNITY_C)
-	@ echo -e "$(WHITE_BOLD)Linking test binary$(WHITE)...$(RESETCOLOR)"
-	@ $(LINK) -DUNITY_OUTPUT_COLOR $(TEST_OBJ_FILES) $(OBJ_FILES_NOMAIN) $(UNITY_C) -o $(TEST_BUILD_DIR)/test.out
-	@ echo -e "$(WHITE_BOLD)Running tests$(WHITE)...$(RESETCOLOR)"
-	@ ./$(TEST_BUILD_DIR)/test.out
+# Link final test binary.
+$(TEST_BUILD_DIR)/test_%.out: $(TEST_OBJ_DIR)/test_%.o $(OBJ_DIR)/grammar.o $(OBJ_FILES_NOMAIN) $(UNITY_OBJ)
+	@ mkdir -p $(TEST_BUILD_DIR)
+	@ $(PRINT) "$(WHITE_BOLD)Linking test binary $(WHITE)$@$(WHITE_BOLD)...$(RESETCOLOR)"
+	$(LINK) -o $@ $? $(LDFLAGS)
 
+# Run the test files.
+test: $(TARGET) $(TEST_BIN_FILES)
+	@ $(PRINT) "$(WHITE_BOLD)Running unit tests...$(RESETCOLOR)"
+	for test in $(TEST_BIN_FILES); do ./$${test} || echo -e "$(RED_BOLD) BAD EXIT ON $${test} $(RESETCOLOR)"; done
+	@ $(PRINT) "$(WHITE_BOLD)Running validation tests...$(RESETCOLOR)"
+	$(BATS) $(TEST_VAL_DIR)
+
+# Clean out objects, binaries, and built artifacts.
 clean:
-	@ echo -e "$(WHITE_BOLD)Cleaning up...$(WHITE) $(OBJ_DIR)/*.o $(TEST_OBJ_DIR)/*.o $(TEST_BUILD_DIR)/test.out $(TARGET) $(GRAM_DIR)/* $(RESETCOLOR)"
-	@ rm -rf $(OBJ_DIR)/*.o $(TEST_OBJ_DIR)/*.o $(TEST_BUILD_DIR)/test.out $(TARGET) $(GRAM_DIR)/*
+	@ $(PRINT) "$(WHITE_BOLD)Cleaning up...$(RESETCOLOR)"
+	rm -rf $(OBJ_DIR)/*.o $(TEST_OBJ_DIR)/*.o $(TEST_BUILD_DIR)/test.out $(TARGET) $(GRAM_DIR)/* $(UNITY_OBJ)
 
-.PHONY: all clean test nocolor release run
+# Get LOC.
+lines:
+	@ wc -l $(SRC_FILES) $(INC_FILES) $(GRAM_SRC)
+
+.PHONY: all clean test nocolor release run lines
+
+# Run this intermediary even though make thinks it's useless.
+.PRECIOUS: $(TEST_OBJ_FILES)

README.md

@@ -1,15 +1,36 @@
 # SCL: Simple CAS Language
 
-## Current State
+Version v0.3
 
-The following things are possible:
-  1. Floating-point numbers
-  2. Negative numbers
-  3. Addition
-  4. Subtraction
-  5. Multiplication
+SCL aims to be a human-friendly Computer Algebra System (CAS) inspired by
+[maxima](https://maxima.sourceforge.io/) that feels like writing on paper. In
+its current state, SCL can be used as a functional programming language capable
+of performing simple arithmetic. The codebase is about 2,000 lines of C,
+including a parser, interpreter, and runtime. It uses a linked environment
+scoping model.
 
-## Syntax (Planned)
+## Usage
+
+To download and run:
+
+```bash
+git clone https://git.signorovitch.org/jacob/scl -b stable && cd scl
+make release
+./scl.out
+```
+
+### For Development
+
+```bash
+git clone git@signorovitch.org:jacob/scl --recurse-submodules && cd scl
+make all test
+./scl.out
+```
+
+If you wish to run tests, make sure to run `git clone --recurse-submodules` to
+include the [Unity](https://github.com/ThrowTheSwitch/Unity) test framework.
+
+## Syntax
 
 As one would expect, you can evaluate simple infix expressions:
 
@@ -18,36 +39,36 @@ As one would expect, you can evaluate simple infix expressions:
 = 2
 ```
 
-You can also define your own functions:
+You can also define your own functions and variables:
 
 ```scl
-> f(x) = 2x
-> f(2)
+> f(x) 2 * x
+> n = 3
+> f(n)
+= 6
+```
+
+Being a functional programming language at heart, one can of course use lambda functions:
+
+```scl
+> (\(x) 2 * x)(5)
+= 10
+> f(g) g(2)
+> f(\(x) 2 * x)
 = 4
 ```
 
-Symbolic algebra is done in the following manner:
+Here's a simple factorial function:
 
 ```scl
-> f(x) = x^4
-> diff(f, x:sym, 2)
-= 12x^2
+> factorial(n) {
+>   if (n == 0) { 1 }
+>   else { n * factorial(n - 1) }
+> }
 ```
 
-SCL will dynamically decide on types, but you can state them explicitly as
-well:
+Or, using SCL's more concise syntax:
 
 ```scl
-> f(x:int) = 2x
-> f(2.2)
-! f(x:int): x must be of type int.
-```
-
-Variables can be defined, with several attributes:
-
-```scl
-> a = 1             // Interpret type automatically.
-> b:int = 1         // Must be int.
-> c:const:int = 1   // Constant: value can never change.
-> x:sym             // Treated symbolicaly.
+> factorial(n) ? n == 0 1 n * factorial(n - 1)
 ```

STATUS.md

@@ -0,0 +1,55 @@
+# SCL Design Status
+
+- [x] Data definitions
+  - [x] Token Definitions
+  - [x] AST Definitions
+
+- [ ] Parser
+  - [x] Parse numbers
+  - [x] Parse floats
+  - [x] Parse negative numbers
+  - [x] Parse infix operators
+  - [x] Order of operations
+  - [x] Parse function application
+  - [x] Parse order of operations with parenthesis
+  - [x] Parse variable invocation
+  - [x] Parse variable definition
+    - [ ] Parse types
+  - [x] Parse function definition
+  - [ ] Parse lists/arrays/vectors
+  - [x] Parse blocks
+  - [ ] Parse control flow
+    - [ ] Parse `if` statements
+    - [ ] Parse `loop`s
+    - [ ] Parse `for` loops
+    - [ ] Parse `while` loops
+    - [ ] Parse `case` statements
+    - [ ] Parse `goto` statements
+  - [ ] Parse lambda function definition
+  - [ ] Parse function calling with positional arguments
+  - [ ] Parse variadic functions
+  - [ ] Parse infix function definition
+
+- [ ] Executer
+  - [x] Exec function calls
+  - [x] Exec variable use
+  - [x] Exec variable definition
+  - [x] Exec function definition
+  - [ ] Exec symbolic variables
+  - [ ] Exec control flow statements
+  - [ ] Exec variadic functions
+  - [ ] Exec lambda functions
+  - [ ] Exec lists
+  - [ ] Exec arrays
+  - [ ] Exec vectors
+
+- [ ] Interface
+  - [ ] Interactive interpreter
+    - [ ] Use GNU readline
+    - [ ] Multi-line input
+    - [ ] Syntax highlighting
+    - [ ] Autocompletion/suggestion
+  - [ ] Command line interface
+    - [ ] Pass in a file
+    - [ ] Save AST to a file
+    - [ ] Run from AST file

TODO.md

@@ -0,0 +1,9 @@
+EXCEPTION HANDLING: exception ast type should have as data a giant enum of
+possible types, rather than a char* message. A description of each type could be
+handled under the exception type and print logic. For now, executor checks
+message for special exceptions e.g. exit().
+
+Change editor to GNU Readline.
+Make variables persist through lines in the editor.
+
+Return syntax errors as exceptions.

config.mk

@@ -0,0 +1,40 @@
+NAME = scl
+
+TARGET = $(NAME).out
+
+SRC_DIR = src
+INC_DIR = $(SRC_DIR)/include
+BUILD_DIR = build
+OBJ_DIR = $(BUILD_DIR)/obj
+GRAM_DIR = $(BUILD_DIR)/grammars
+TEST_DIR = test
+TEST_BUILD_DIR = $(BUILD_DIR)/test
+TEST_OBJ_DIR = $(TEST_BUILD_DIR)/obj
+
+CC = clang -std=c23
+LINK = clang
+CFLAGS = -Wall -DDBG -ggdb -fsanitize=leak
+LDFLAGS = -lm
+BATS = bats
+BISON = bison
+PRINT = echo -e
+
+SRC_FILES = $(wildcard $(SRC_DIR)/*.c)
+INC_FILES = $(wildcard $(INC_DIR)/*.h)
+OBJ_FILES = $(patsubst $(SRC_DIR)/%.c, $(OBJ_DIR)/%.o, $(SRC_FILES))
+OBJ_FILES_NOMAIN = $(filter-out $(OBJ_DIR)/main.o, $(OBJ_FILES)) # Object files without main.c.
+GRAM_SRC = $(SRC_DIR)/grammar.y
+GRAM_FILES = $(GRAM_DIR)/grammar.tab.c $(GRAM_DIR)/grammar.tab.h
+UNITY_DIR = $(TEST_DIR)/Unity
+UNITY_C = $(UNITY_DIR)/src/unity.c
+UNITY_H = $(UNITY_DIR)/src/unity.h
+UNITY_OBJ = $(TEST_BUILD_DIR)/unity.o
+TEST_SRC_FILES = $(wildcard $(TEST_DIR)/*.c)
+TEST_OBJ_FILES = $(patsubst $(TEST_DIR)/%.c, $(TEST_OBJ_DIR)/%.o, $(TEST_SRC_FILES))
+TEST_BIN_FILES = $(patsubst $(TEST_DIR)/%.c, $(TEST_BUILD_DIR)/%.out, $(TEST_SRC_FILES))
+TEST_VAL_DIR = $(TEST_DIR)/val
+
+RESETCOLOR = \033[0m
+WHITE = $(RESETCOLOR)\033[37m
+WHITE_BOLD = $(RESETCOLOR)\033[37;1m
+RED_BOLD = $(RESETCOLOR)\033[31;1m

definitions.md

@@ -0,0 +1,25 @@
+f = \(x) 2 * x
+g = \(h) \(x) h(h(x))
+
+f(2) => 4
+g(f)(2) => 8
+
+CALL
+ argc: 1
+ argv: [ 2 ]
+ to:
+  CALL
+   argc: 1
+   argv: [
+    VREF
+     name: f
+   ]
+   to:
+    VREF
+     name: g
+ fname: NULL
+
+
+expression + arguments = call = expression
+expression + parameters = lambda = expression
+expression + name = variable = expression

examples/function.scl

@@ -0,0 +1,2 @@
+apply(f, x) f(x)
+apply(\(x) x + 1, 2)

examples/types.scl

@@ -0,0 +1,48 @@
+# Vectors
+# - Must have fixed size and type
+
+# Lists
+# - Variable size, variable type
+
+# Define a variable of type int:
+n: int = 3
+
+# Define v as a 3-dimensional vector of integers:
+v: int<3> = <4, 5, 6>
+
+# Define l as list of length 3:
+l: [3] = [1, 2, "These can be any type at all"]
+# This would also work, as length values for lists are optional (and mutable),
+# unlike vectors:
+l: [] = [1, 2, "whatever"]
+# This is also the same, being more explicit about the any type:
+l: any[] = [1, 2, "whatever"]
+# This must be a list of integers, however:
+l: int[] = [1, 2, 3]
+
+# Define a list of either integers or strings:
+l: union(int, str)[] = ["hello", 4, "world"]
+# union() is a complex type generator; "returns" a union of the int and str types.
+
+# Use vectors wherever possible, as they are much faster than lists.
+
+# Matrix
+# - Must have a fixed size and type (just like vectors)
+m: int<2, 2> = <<0, 1>, <2, 3>>
+# Can also be written as
+m: int<2, 2> = <<0, 1, 2, 3>>
+# When using this syntax, will fill remaining space with default value of type
+# to make data rectangular. E.g., to fill a 2 x 2 matrix with 0:
+m: int<2, 2> = <<>>
+
+# To define custom data types, e.g. structs:
+typedef(Vec2, struct( a: int, b: int ))
+vector_two: Vec2 = Vec2(2, 3)
+
+typedef(IntOrStr, union(str, int))
+one: IntOrStr = 1
+alsoOne: IntOrStr = "one"
+
+# To define custom data types with type arguments:
+typedef(Vec1Of(T), T<1>)
+hello: Vec1Of(str) = <"Hello">

src/ast.c

@@ -1,21 +1,36 @@
+#include <inttypes.h>
 #include <stdio.h>
 
 #include "include/ast.h"
-#include "include/dstr.h"
+#include "include/gc.h"
+#include "include/scope.h"
 #include "include/util.h"
 
 extern AST* root;
 
-static char* asttype_names[] = {
-    [AST_TYPE_CALL] = "CALL",
-    [AST_TYPE_NUM] = "NUMBER",
-};
-
 AST* ast_init(ASTType type, void* data) {
+    AST* ast = gc_alloc(sizeof(AST), GC_TYPE_AST);
+
+    ast->type = type;
+    ast->data = data;
+    ast->scope = NULL;
+
+    if (ast->type > AST_TYPE_MAX) {
+        log_dbgf(
+            "Attempted to create invalid AST (%i > %i) to GC: ast:%p",
+            ast->type, AST_TYPE_MAX, ast
+        );
+    }
+
+    return ast;
+}
+
+AST* ast_init_scope(ASTType type, void* data, Scope* scope) {
     AST* ast = malloc(sizeof(AST));
 
     ast->type = type;
     ast->data = data;
+    ast->scope = scope;
 
     return ast;
 }
@@ -24,60 +39,85 @@ void ast_destroy(AST* ast) {
     if (!ast) return;
 
     switch (ast->type) {
-        case AST_TYPE_NUM:  ast_num_data_destroy(ast->data); break;
-        case AST_TYPE_CALL: ast_call_data_destroy(ast->data); break;
+        case AST_TYPE_NUM:    ast_num_data_destroy(ast->data); break;
+        case AST_TYPE_BOOL:   ast_bool_data_destroy(ast->data); break;
+        case AST_TYPE_CALL:   ast_call_data_destroy(ast->data); break;
+        case AST_TYPE_VREF:   ast_vref_data_destroy(ast->data); break;
+        case AST_TYPE_VDEF:   ast_vdef_data_destroy(ast->data); break;
+        case AST_TYPE_BLOCK:  ast_block_data_destroy_psv(ast->data); break;
+        case AST_TYPE_FDEF:   ast_fdef_data_destroy_psv(ast->data); break;
+        case AST_TYPE_ARG:    ast_arg_data_destroy(ast->data); break;
+        case AST_TYPE_BIF:    ast_bif_data_destroy(ast->data); break;
+        case AST_TYPE_EXC:    ast_exc_data_destroy(ast->data); break;
+        case AST_TYPE_LAMBDA: ast_lambda_data_destroy(ast->data); break;
         default:
             log_dbgf("Unknown ast type %d (max: %d)", ast->type, AST_TYPE_MAX);
     }
-}
 
-void ast_print(AST* ast) { ast_print_i(ast, 0); }
-
-void ast_print_i(AST* ast, int i) {
-    INDENT_BEGIN(i);
-
-    INDENT_TITLE("AST", ast);
-    INDENT_FIELD("type", "%s", asttype_names[ast->type]);
-    INDENT_FIELD_EXT_NONL_START("data");
-    switch (ast->type) {
-        case AST_TYPE_NUM:
-            printf("%s  %lf\n", INDENT_spacing->buf, *(ASTNumData*)ast->data);
-            break;
-        case AST_TYPE_CALL: ast_call_print(ast->data, i + 2); break;
-        default:            exit(1);
-    }
-    INDENT_FIELD_NONL_END;
-    INDENT_END;
+    free(ast);
 }
 
 ASTNumData* ast_num_data_init(double val) {
     talloc(ASTNumData, num);
 
-    log_dbgf("val: %lf", val);
-
     *num = val;
 
     return num;
 }
 
-void ast_num_data_destroy(ASTNumData* num) {
-    if (!num) return free(num);
+void ast_num_data_destroy(ASTNumData* num) { free(num); }
+
+ASTBoolData* ast_bool_data_init(int val) {
+    talloc(ASTBoolData, bol);
+
+    *bol = val;
+
+    return bol;
 }
 
-void ast_num_print(ASTNumData* data, int i) {
-    INDENT_BEGIN(i);
+void ast_bool_data_destroy(ASTBoolData* bol) { free(bol); }
 
-    INDENT_FIELD("data", "%lf", *data);
-
-    INDENT_END;
+ASTExcData* ast_exc_data_init(const char* msg, AST* trace) {
+    ASTExcData* data = malloc(sizeof(ASTExcData));
+    data->msg = msg;
+    data->trace = trace;
+    return data;
 }
 
-ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv) {
+void ast_exc_data_destroy(ASTExcData* exc) {
+    // `msg` is static, and `trace` will get freed in GC.
+    free(exc);
+}
+
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*)) {
+    return (ASTBIFData*)fn;
+}
+
+void ast_bif_data_destroy(ASTBIFData* bif) { return; }
+
+// Lambda.
+
+ASTLambdaData* ast_lambda_data_init(size_t parc, AST** parv, AST* body) {
+    talloc(ASTLambdaData, lambda);
+
+    lambda->parc = parc;
+    lambda->parv = parv;
+    lambda->body = body;
+
+    return lambda;
+}
+
+void ast_lambda_data_destroy(ASTLambdaData* lambda) {
+    free(lambda->parv);
+    free(lambda);
+}
+
+// Call.
+
+ASTCallData* ast_call_data_init(size_t argc, AST** argv, AST* exp) {
     talloc(ASTCallData, call);
 
-    log_dbgf("to: %s", to);
-
-    call->to = to;
+    call->exp = exp;
     call->argc = argc;
     call->argv = argv;
 
@@ -85,18 +125,101 @@ ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv) {
 }
 
 void ast_call_data_destroy(ASTCallData* call) {
-    if (!call) return free(call->to);
-    for (size_t i = 0; i < call->argc; i++) free(call->argv[i]);
+    if (!call) return;
+    free(call->argv);
     free(call);
 }
 
-void ast_call_print(ASTCallData* data, int i) {
-    INDENT_BEGIN(i);
+// VDef.
 
-    INDENT_TITLE("ASTCallData", data);
-    INDENT_FIELD("to", "%s", data->to);
-    INDENT_FIELD("argc", "%ld", data->argc);
-    INDENT_FIELD_LIST("argv", data->argv, data->argc, ast_print_i);
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp) {
+    talloc(ASTVDefData, vdef);
 
-    INDENT_END;
+    vdef->name = name;
+    vdef->exp = exp;
+
+    return vdef;
+}
+
+void ast_vdef_data_destroy(ASTVDefData* vdef) {
+    free(vdef->name);
+    free(vdef);
+}
+
+// VRef.
+
+ASTVrefData* ast_vref_data_init(char* to) {
+    talloc(ASTVrefData, vref);
+
+    vref->to = to;
+
+    return vref;
+}
+
+void ast_vref_data_destroy(ASTVrefData* vref) {
+    free(vref->to);
+    free(vref);
+}
+
+ASTBlockData* ast_block_data_init(AST** inside, size_t ln) {
+    ASTBlockData* block = malloc(sizeof(ASTBlockData));
+
+    block->inside = inside;
+    block->ln = ln;
+
+    return block;
+}
+
+void ast_block_data_destroy(ASTBlockData* block) {
+    for (size_t i = 0; i < block->ln; i++) { ast_destroy(block->inside[i]); }
+
+    free(block->inside);
+    free(block);
+}
+
+void ast_block_data_destroy_psv(ASTBlockData* block) {
+    free(block->inside);
+    free(block);
+}
+
+ASTFDefData*
+ast_fdef_data_init(char* name, size_t argc, AST** argv, AST* body) {
+    ASTFDefData* fdef = malloc(sizeof(ASTFDefData));
+
+    fdef->name = name;
+    fdef->argc = argc;
+    fdef->argv = argv;
+    fdef->body = body;
+
+    return fdef;
+}
+
+void ast_fdef_data_destroy(ASTFDefData* fdef) {
+    free(fdef->name);
+    for (int i = 0; i < fdef->argc; ast_destroy(fdef->argv[i++]));
+    ast_destroy(fdef->body);
+}
+
+void ast_fdef_data_destroy_psv(ASTFDefData* fdef) {
+    free(fdef->name);
+    free(fdef->argv);
+    free(fdef);
+}
+
+ASTArgData* ast_arg_data_init(char* name) {
+    ASTArgData* arg = malloc(sizeof(ASTArgData));
+    arg->name = name;
+    return arg;
+}
+
+void ast_arg_data_destroy(ASTArgData* arg) { free(arg->name); }
+
+AST* ast_find(Scope* scope, char* name) {
+    while (scope) {
+        AST* gotten = htab_get(scope->here, name);
+        if (gotten) return gotten;
+        else scope = scope->inherit;
+    }
+
+    return NULL;
 }

src/ast_print.c

@@ -0,0 +1,175 @@
+#include "include/ast_print.h"
+#include "include/ast.h"
+#include "include/builtin.h"
+#include "include/dstr.h"
+#include "include/util.h"
+#include <stdio.h>
+
+static char* asttype_names[] = {
+    [AST_TYPE_CALL] = "FUNC CALL",
+    [AST_TYPE_NUM] = "NUMBER",
+    [AST_TYPE_BOOL] = "BOOLEAN",
+    [AST_TYPE_VREF] = "VAR REFERENCE",
+    [AST_TYPE_VDEF] = "VAR DEFINITION",
+    [AST_TYPE_BLOCK] = "BLOCK",
+    [AST_TYPE_EXC] = "EXCEPTION",
+    [AST_TYPE_FDEF] = "FUNCTION DEFINITION",
+    [AST_TYPE_ARG] = "DEFINITION ARGUMENT",
+    [AST_TYPE_LAMBDA] = "LAMBDA EXPRESSION",
+    [AST_TYPE_BIF] = "BUILTIN FUNCTION"
+};
+
+void ast_print(AST* ast) {
+    if (!ast) return;
+    ast_print_i(ast, 0);
+}
+
+void ast_print_i(AST* ast, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("AST", ast);
+    INDENT_FIELD("type", "%s", asttype_names[ast->type]);
+    INDENT_FIELD_EXT_NONL_START("data");
+    switch (ast->type) {
+        case AST_TYPE_NUM:
+            printf("%s  %lf\n", INDENT_spacing->buf, *(ASTNumData*)ast->data);
+            break;
+        case AST_TYPE_BOOL:
+            printf(
+                "%s  %s\n", INDENT_spacing->buf,
+                *(ASTBoolData*)ast->data ? "true" : "false"
+            );
+            break;
+        case AST_TYPE_CALL:   ast_call_print(ast->data, i + 2); break;
+        case AST_TYPE_EXC:    ast_exc_print(ast->data, i + 2); break;
+        case AST_TYPE_VREF:   ast_vref_print(ast->data, i + 2); break;
+        case AST_TYPE_VDEF:   ast_vdef_print(ast->data, i + 2); break;
+        case AST_TYPE_BLOCK:  ast_block_print(ast->data, i + 2); break;
+        case AST_TYPE_FDEF:   ast_fdef_print(ast->data, i + 2); break;
+        case AST_TYPE_ARG:    ast_arg_print(ast->data, i + 2); break;
+        case AST_TYPE_LAMBDA: ast_lambda_print(ast->data, i + 2); break;
+        case AST_TYPE_BIF:    ast_bif_print(ast->data, i + 2); break;
+        default:              exit(1);
+    }
+    INDENT_FIELD_NONL_END;
+    INDENT_END;
+}
+
+void ast_num_print(ASTNumData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_FIELD("data", "%lf", *data);
+
+    INDENT_END;
+}
+
+void ast_bool_print(ASTBoolData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_FIELD("data", "%s", *data ? "true" : "false");
+
+    INDENT_END;
+}
+
+void ast_exc_print(ASTExcData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTExcData", data);
+    INDENT_FIELD("msg", "\"%s\"", data->msg);
+    if (data->trace == NULL) {
+        INDENT_FIELD("trace", "%p", NULL)
+    } else {
+        INDENT_FIELD_EXT_NONL_START("trace");
+        ast_print_i(data->trace, i + 1);
+        INDENT_FIELD_NONL_END;
+    }
+    INDENT_END;
+}
+
+void ast_call_print(ASTCallData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTCallData", data);
+    INDENT_FIELD("argc", "%ld", data->argc);
+    INDENT_FIELD_LIST("argv", data->argv, data->argc, ast_print_i);
+    INDENT_FIELD_EXT_NONL_START("exp");
+    ast_print_i(data->exp, i + 2);
+    INDENT_FIELD_NONL_END;
+
+    INDENT_END;
+}
+void ast_vdef_print(ASTVDefData* vdef, int depth) {
+    INDENT_BEGIN(depth);
+
+    INDENT_TITLE("ASTVDefData", vdef);
+    INDENT_FIELD("name", "%s", vdef->name);
+    INDENT_FIELD_EXT_NONL_START("exp");
+    ast_print_i(vdef->exp, depth + 2); // 2 because already indented.
+    INDENT_FIELD_NONL_END;
+
+    INDENT_END;
+}
+
+void ast_vref_print(ASTVrefData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTVrefData", data);
+    INDENT_FIELD("to", "%s", data->to);
+
+    INDENT_END;
+}
+
+void ast_block_print(ASTBlockData* data, int depth) {
+    INDENT_BEGIN(depth);
+
+    INDENT_TITLE("ASTBlockData", data);
+    INDENT_FIELD("ln", "%ld", data->ln);
+    INDENT_FIELD_LIST("inside", data->inside, data->ln, ast_print_i);
+
+    INDENT_END;
+}
+
+void ast_fdef_print(ASTFDefData* fdef, int i) {
+    INDENT_BEGIN(i)
+    INDENT_TITLE("ASTFDefData", fdef);
+    INDENT_FIELD("name", "%s", fdef->name);
+    INDENT_FIELD("argc", "%ld", fdef->argc);
+    INDENT_FIELD_LIST("argv", fdef->argv, fdef->argc, ast_print_i);
+    INDENT_FIELD_EXT_NONL_START("body");
+    ast_print_i(fdef->body, i + 2);
+    INDENT_FIELD_NONL_END;
+    INDENT_END;
+}
+void ast_arg_print(ASTArgData* arg, int i) {
+    INDENT_BEGIN(i);
+    INDENT_TITLE("ASTArgData", arg);
+    INDENT_FIELD("name", "%s", arg->name);
+    INDENT_END;
+}
+
+void ast_lambda_print(ASTLambdaData* lambda, int i) {
+    INDENT_BEGIN(i)
+    INDENT_TITLE("ASTLambdaData", lambda);
+    INDENT_FIELD("parc", "%ld", lambda->parc);
+    INDENT_FIELD_LIST("parv", lambda->parv, lambda->parc, ast_print_i);
+    INDENT_FIELD_EXT_NONL_START("body");
+    ast_print_i(lambda->body, i + 2);
+    INDENT_FIELD_NONL_END;
+    INDENT_END;
+}
+
+void ast_bif_print(ASTBIFData* bif, int i) {
+    INDENT_BEGIN(i);
+    INDENT_TITLE("ASTBIFData", bif);
+
+    char* name = "unknown";
+
+    for (int i = 0; i < BUILTIN_FNS_LN; i++)
+        if ((void*)BUILTIN_FNS[i].fn == bif) {
+            name = BUILTIN_FNS[i].name;
+            break;
+        }
+
+    INDENT_FIELD("name", "%s", name);
+    INDENT_END;
+}

src/builtin.c

@@ -0,0 +1,211 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "include/ast.h"
+#include "include/ast_print.h"
+#include "include/builtin.h"
+#include "include/exec.h"
+#include "include/util.h"
+
+AST* builtin_sum(size_t argc, AST** argv, Scope* parent) {
+    ASTNumData total = 0;
+
+    for (int i = 0; i < argc; i++) {
+        AST* arg = exec_exp(argv[i], parent);
+        if (arg->type == AST_TYPE_EXC)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("`sum` encountered an exception.", arg)
+            );
+        if (arg->type != AST_TYPE_NUM)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("Sum can't sum some non-num arguments.", NULL)
+            );
+
+        total += *(ASTNumData*)arg->data;
+    }
+
+    return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
+}
+
+AST* builtin_sub(size_t argc, AST** argv, Scope* parent) {
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
+    AST* first = exec_exp(*argv, parent);
+    if (first->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("`sub` encountered an exception.", first)
+        );
+    if (first->type != AST_TYPE_NUM)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("Can't subtract non-num arguments.", NULL)
+        );
+
+    ASTNumData total = *(ASTNumData*)first->data;
+
+    for (int i = 1; i < argc; i++) {
+        AST* arg = exec_exp(argv[i], parent);
+        if (arg->type == AST_TYPE_EXC)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("`sub` encountered an exception.", arg)
+            );
+        if (arg->type != AST_TYPE_NUM)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("Can't subtract non-num arguments.", NULL)
+            );
+
+        total -= *(ASTNumData*)arg->data;
+    }
+
+    return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
+}
+
+AST* builtin_mul(size_t argc, AST** argv, Scope* parent) {
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
+    AST* first = exec_exp(*argv, parent);
+    if (first->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("`mul` encountered an expection.", first)
+        );
+    if (first->type != AST_TYPE_NUM)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("Can't multiply non-num arguments.", NULL)
+        );
+
+    ASTNumData total = *(ASTNumData*)first->data;
+
+    for (int i = 1; i < argc; i++) {
+        AST* arg = exec_exp(argv[i], parent);
+        if (arg->type == AST_TYPE_EXC)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("`mul` encountered an execption.", arg)
+            );
+        if (arg->type != AST_TYPE_NUM)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("Can't multiply non-num arguments.", NULL)
+            );
+
+        total *= *(ASTNumData*)arg->data;
+    }
+
+    return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
+}
+
+AST* builtin_div(size_t argc, AST** argv, Scope* parent) {
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
+    AST* first = exec_exp(*argv, parent);
+    if (first->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("`div` encountered an exception.", first)
+        );
+    if (first->type != AST_TYPE_NUM)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("Can't divide non-num arguments.", NULL)
+        );
+
+    ASTNumData total = *(ASTNumData*)first->data;
+
+    for (int i = 1; i < argc; i++) {
+        AST* arg = exec_exp(argv[i], parent);
+        if (arg->type == AST_TYPE_EXC)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("`div` encountered an exception.", arg)
+            );
+        if (arg->type != AST_TYPE_NUM)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("Can't divide non-num arguments.", NULL)
+            );
+
+        total /= *(ASTNumData*)arg->data;
+    }
+
+    return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
+}
+
+AST* builtin_die(size_t argc, AST** argv, Scope* parent) {
+    return ast_init(AST_TYPE_EXC, ast_exc_data_init("8", NULL));
+}
+
+AST* builtin_if(size_t argc, AST** argv, Scope* parent) {
+    if (argc != 3)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("If invoked with too few args.", NULL)
+        );
+
+    AST* pred = exec_exp(argv[0], parent);
+    AST* body = argv[1];
+    AST* alt = argv[2];
+
+    if (pred->type != AST_TYPE_BOOL) {
+        if (pred->type == AST_TYPE_EXC) {
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("if touched an error", pred)
+            );
+        } else {
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("if works on booleans idiot", NULL)
+            );
+        }
+    }
+
+    if (*(ASTBoolData*)pred->data) return exec_exp(body, parent);
+    else return exec_exp(alt, parent);
+}
+
+AST* builtin_eq(size_t argc, AST** argv, Scope* parent) {
+    if (argc < 1) return ast_init(AST_TYPE_EXC, ast_exc_data_init("bad", NULL));
+    else if (argc == 1) return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+
+    AST* first = exec_exp(argv[0], parent);
+    ASTType type = first->type;
+
+    AST* second = exec_exp(argv[1], parent);
+    if (first->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC, ast_exc_data_init("first was bad", first)
+        );
+    if (second->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC, ast_exc_data_init("second was bad", second)
+        );
+
+    if (second->type != type)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("apples and oranges or something idk", NULL)
+        );
+    // Later when I put together an anctual type system I'll have this
+    // delegated to each type. For now this works.
+
+    switch (type) {
+        case AST_TYPE_NUM:
+            if (*(ASTNumData*)first->data == *(ASTNumData*)second->data)
+                return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+            else return ast_init(AST_TYPE_BOOL, ast_bool_data_init(0));
+        case AST_TYPE_BOOL:
+            if (*(ASTNumData*)first->data == *(ASTNumData*)second->data)
+                return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+            else return ast_init(AST_TYPE_BOOL, ast_bool_data_init(0));
+        default:
+            return ast_init(
+                AST_TYPE_BOOL, ast_bool_data_init(0)
+            ); // Can't equate nonprimatives. I think. Maybe.
+    }
+}

src/dlist.c

@@ -0,0 +1,44 @@
+#include <stddef.h>
+#include <stdio.h> // IWYU pragma: keep. Req by util macros.
+
+#include "include/dlist.h"
+#include "include/util.h"
+
+DList* dlist_init(void) {
+    DList* dlist = malloc(sizeof(DList));
+
+    dlist->sz = DLIST_INITSZ;
+    dlist->buf = malloc(DLIST_INITSZ);
+    dlist->ln = 0;
+
+    return dlist;
+}
+
+void dlist_destroy(DList* dlist) {
+    free(dlist->buf);
+    free(dlist);
+}
+
+void dlist_destroypsv(DList* dlist) { free(dlist); }
+
+// Check whether the buffer is about to overflow and resize it if necessary.
+void dlist_check_resz(DList* dlist) {
+    while ((dlist->ln + 1) * sizeof(void*) >= dlist->sz) {
+        // Double the buffer size when overflown.
+        dlist->sz *= 2;
+        dlist->buf = realloc(dlist->buf, dlist->sz);
+        log_dbgf(
+            "dlist @ %p doubled from %ld to %ld", dlist, dlist->sz / 2,
+            dlist->sz
+        );
+    }
+}
+
+void dlist_append(DList* dest, void* src) {
+    dlist_check_resz(dest);
+
+    log_dbgf("added %p to dlist@%p", src, dest);
+
+    dest->buf[dest->ln] = src;
+    dest->ln++;
+}

src/dstr.c

@@ -1,13 +1,14 @@
 #include "include/dstr.h"
 #include "include/util.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
 Dstr* dstr_init(void) {
     Dstr* dstr = malloc(sizeof(Dstr));
 
-    dstr->bufsz = DSTR_INITSZ;
+    dstr->sz = DSTR_INITSZ;
     dstr->buf = malloc(DSTR_INITSZ);
     *dstr->buf = '\0';
     dstr->ln = 0;
@@ -20,16 +21,22 @@ void dstr_destroy(Dstr* dstr) {
     free(dstr);
 }
 
-void dstr_append(Dstr* dest, char* src, size_t ln) {
-    while (dest->ln + ln + 1 > dest->bufsz) {
+void dstr_destroypsv(Dstr* dstr) { free(dstr); }
+
+// Check whether the buffer is overflowing and resize it if necessary.
+void dstr_check_resz(Dstr* dstr, size_t ln) {
+    while (dstr->ln + ln + 1 > dstr->sz) {
         // Double the buffer size when overflown.
-        dest->bufsz *= 2;
-        dest->buf = realloc(dest->buf, dest->bufsz);
+        dstr->sz *= 2;
+        dstr->buf = realloc(dstr->buf, dstr->sz);
         log_dbgf(
-            "dstr @ %p doubled from %ld to %ld", dest, dest->bufsz / 2,
-            dest->bufsz
+            "dstr @ %p doubled from %ld to %ld", dstr, dstr->sz / 2, dstr->sz
         );
     }
+}
+
+void dstr_append(Dstr* dest, char* src, size_t ln) {
+    dstr_check_resz(dest, ln);
 
     // Overwrites the \0 at the end of the string, keeps the null from the given
     // string.
@@ -38,15 +45,7 @@ void dstr_append(Dstr* dest, char* src, size_t ln) {
 }
 
 void dstr_appendch(Dstr* dest, char ch) {
-    if (dest->ln + 1 + 1 > dest->bufsz) {
-        // Double the buffer size when overflown.
-        dest->bufsz *= 2;
-        dest->buf = realloc(dest->buf, dest->bufsz);
-        log_dbgf(
-            "dstr @ %p doubled from %ld to %ld", dest, dest->bufsz / 2,
-            dest->bufsz
-        );
-    }
+    dstr_check_resz(dest, 1);
 
     // Overwrites the preexisting null terminator, and adds one of its own.
     dest->buf[dest->ln] = ch;

src/exec.c

@@ -1,44 +1,154 @@
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "include/ast.h"
+#include "include/builtin.h"
 #include "include/exec.h"
+#include "include/htab.h"
+#include "include/scope.h"
 #include "include/util.h"
 
-extern AST* root;
-
-ASTNumData exec_expr(AST* ast) {
-    // ast_print(ast);
+AST* exec_start(AST* ast) {
     log_dbg("Started execution.");
+
+    if (!ast) return ast;
+
+    Scope* global = scope_init(NULL);
+    global->uses = 1;
+
+    for (int i = 0; i < BUILTIN_FNS_LN; i++)
+        htab_ins(
+            global->here, BUILTIN_FNS[i].name,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(BUILTIN_FNS[i].fn))
+        );
+
+    log_dbg("Completed startup sequence.");
+
+    AST* res = exec_exp(ast, global);
+
+    return res;
+}
+
+AST* exec_exp(AST* ast, Scope* parent) {
     switch (ast->type) {
-        case AST_TYPE_CALL: return exec_call(ast);
-        case AST_TYPE_NUM:  return *(ASTNumData*)ast->data;
-        default:            printf("what\n");
+        case AST_TYPE_BLOCK: return exec_block(ast, parent);
+        case AST_TYPE_CALL:  return exec_call(ast, parent);
+        case AST_TYPE_NUM:
+            return ast_init(
+                AST_TYPE_NUM, ast_num_data_init(*(ASTNumData*)ast->data)
+            );
+        case AST_TYPE_BOOL:
+            return ast_init(
+                AST_TYPE_BOOL, ast_bool_data_init(*(ASTBoolData*)ast->data)
+            );
+        case AST_TYPE_VREF:   return exec_vref(ast, parent);
+        case AST_TYPE_VDEF:   return exec_vdef(ast, parent);
+        case AST_TYPE_FDEF:   return exec_fdef(ast, parent);
+        case AST_TYPE_BIF:
+        case AST_TYPE_LAMBDA: return ast;
+        default:              printf("what\n"); exit(1);
     }
 }
 
-ASTNumData exec_call(AST* ast) {
-    log_dbg("Started call execution.");
-    fflush(stdout);
+AST* exec_block(AST* ast, Scope* parent) {
+    ASTBlockData* block = (ASTBlockData*)ast->data;
+
+    exec_new_scope(ast, parent);
+
+    // Loop through all but last ast.
+    for (int i = 0; i < block->ln - 1; i++)
+        exec_exp(block->inside[i], ast->scope);
+    AST* last = exec_exp(block->inside[block->ln - 1], ast->scope);
+
+    return last;
+}
+
+AST* exec_call(AST* ast, Scope* parent) {
     ASTCallData* calldata = (ASTCallData*)ast->data;
-    if (!strcmp(calldata->to, "+") && calldata->argc == 2) {
 
-        ASTNumData n1 = exec_expr(calldata->argv[0]);
-        ASTNumData n2 = exec_expr(calldata->argv[1]);
+    AST* exp = exec_exp(calldata->exp, parent);
 
-        return n1 + n2;
-    } else if (!strcmp(calldata->to, "-") && calldata->argc == 2) {
-        ASTNumData n1 = exec_expr(calldata->argv[0]);
-        ASTNumData n2 = exec_expr(calldata->argv[1]);
-
-        return n1 - n2;
-    } else if (!strcmp(calldata->to, "*") && calldata->argc == 2) {
-        ASTNumData n1 = exec_expr(calldata->argv[0]);
-        ASTNumData n2 = exec_expr(calldata->argv[1]);
-
-        return n1 * n2;
+    switch (exp->type) {
+        case AST_TYPE_BIF:
+            ASTBIFData bifdata = exp->data;
+            return bifdata(calldata->argc, calldata->argv, parent);
+        case AST_TYPE_LAMBDA:
+            return exec_lambda(calldata->argc, calldata->argv, exp, parent);
+        default:
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("Uncallable.", NULL)
+            );
     }
-    return -1000;
+}
+
+AST* exec_vdef(AST* ast, Scope* parent) {
+    // Use parent's scope.
+    exec_inherit_scope(ast, parent);
+
+    ASTVDefData* data = (ASTVDefData*)ast->data;
+    AST* val = data->exp;
+    char* key = data->name;
+    scope_add(parent, key, val); // Add variable definition to parent scope.
+    return exec_exp(val, parent);
+}
+
+AST* exec_vref(AST* ast, Scope* parent) {
+    // Use parent's scope.
+    exec_inherit_scope(ast, parent);
+    log_dbg("attempting to reference var");
+    ASTVrefData* vref = (ASTVrefData*)ast->data;
+
+    AST* found = ast_find(parent, vref->to);
+
+    if (found == NULL) {
+        // TODO: Better memory management here.
+        static char msg[256];
+        snprintf(
+            msg, sizeof(msg), "Could not find value in scope for `%s`.",
+            vref->to
+        );
+        return ast_init(AST_TYPE_EXC, ast_exc_data_init(msg, NULL));
+    }
+
+    // return exec_exp(found, ast->scope);
+    return found;
+}
+
+AST* exec_fdef(AST* ast, Scope* parent) {
+    ast->scope = scope_init(parent);
+    ASTFDefData* fdef = (ASTFDefData*)ast->data;
+    AST* val = ast;
+    char* key = fdef->name;
+    scope_add(parent, key, val);
+    return fdef->body; // Function definitions return function body.
+}
+
+AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent) {
+    Scope* callscope = scope_init(parent);
+    ASTLambdaData* lambda = (ASTLambdaData*)exp->data;
+    for (int i = 0; i < argc; i++) {
+        char* key = ((ASTArgData*)lambda->parv[i]->data)->name;
+        AST* val = exec_exp(argv[i], parent);
+        scope_add(callscope, key, val);
+    }
+
+    return exec_exp(lambda->body, callscope);
 }
 
 void exec_print(double n) { printf("= %lf\n", n); }
+
+inline void exec_new_scope(AST* ast, Scope* inherit) {
+    Scope* scope = scope_init(inherit);
+    ast->scope = scope;
+
+    // Update linked status.
+    scope->uses++;
+}
+
+inline void exec_inherit_scope(AST* ast, Scope* inherit) {
+    ast->scope = inherit;
+
+    // Update uses.
+    inherit->uses++;
+}

src/fnv1a.c

@@ -0,0 +1,14 @@
+#include "include/fnv1a.h"
+
+#include <stdlib.h>
+
+uint64_t fnv1a_hash(char* key, size_t ln) {
+    uint64_t hash = FNV1A_BASIS_64;
+
+    for (size_t i = 0; i < ln; i++) {
+        hash ^= (unsigned char)key[i];
+        hash *= FNV1A_PRIME_64;
+    }
+
+    return hash;
+}

src/gc.c

@@ -0,0 +1,57 @@
+#include "include/gc.h"
+#include "include/ast.h"
+#include "include/scope.h"
+#include "include/util.h"
+#include <assert.h>
+#include <stdio.h>
+
+#include <stddef.h>
+
+GC* gclist = NULL;
+
+void gc_destroy(GC* gc) { free(gc); }
+
+void f() {}
+
+void* gc_alloc(size_t sz, GCType type) {
+    assert(type <= GC_TYPE_MAX);
+
+    void* mem = malloc(sz);
+    GC* gc = malloc(sizeof(GC));
+
+    gc->p = mem;
+    gc->type = type;
+    gc->marked = false;
+    gc->nxt = gclist;
+    gclist = gc;
+
+    if (type == GC_TYPE_AST) {
+        log_dbgf("Alloc'd AST for GC: %p", mem);
+    } else if (type == GC_TYPE_SCOPE) {
+        log_dbgf("Alloc'd scope for GC: %p", mem);
+    }
+
+    return mem;
+}
+
+void gc_hack_free() {
+    while (gclist) {
+        GC* gc = gclist;
+        gclist = gclist->nxt;
+        switch (gc->type) {
+            case GC_TYPE_AST:
+                f();
+                if (((AST*)gc->p)->type > AST_TYPE_MAX) {
+                    log_dbgf(
+                        "Attempted to free invalid AST (%i > %i) to GC: gc:%p "
+                        "ast:%p",
+                        ((AST*)gc->p)->type, AST_TYPE_MAX, gc, gc->p
+                    );
+                }
+                ast_destroy(gc->p);
+                break;
+            case GC_TYPE_SCOPE: scope_destroy_psv(gc->p); break;
+        }
+        gc_destroy(gc);
+    }
+}

src/global.c

@@ -0,0 +1,6 @@
+#include "include/global.h"
+
+#include <stdlib.h>
+
+// Global input text.
+char* inp = NULL;

src/grammar.y

@@ -1,7 +1,10 @@
 %{
+    #include <string.h>
     #include <stdio.h>
     #include "../../src/include/ast.h"
     #include "../../src/include/lexer.h"
+    #include "../../src/include/dlist.h"
+    #include "../../src/include/builtin.h"
 
     int yylex(void);
     void yyerror(char const*);
@@ -11,84 +14,307 @@
 
 %code requires {
     #include "../../src/include/ast.h"
+    #include "../../src/include/dlist.h"
+    #include "../../src/include/builtin.h"
 }
 
 %union {
     double fval;
     char* strval;
     AST* ast;
+    ArgArr* argarr;
+    DList* exps;
 }
 
 %define parse.error verbose
 
-%token<strval> CALL
-%token<fval> NUM
+%token BOOLT // Boolean true (TRUE or T).
+%token BOOLF // Boolean false (FALSE or F).
 
-%token NEG
-%token PLUS
-%token MULT
+%token IF // if or ?.
+%token ELSE // else or :.
 
-%token NL
-%type<ast> exp
+%token BLOCKS // Block start {.
+%token BLOCKE // Block end }.
+
+%token GROUPS // Group start (.
+%token GROUPE // Group end ).
+%token SEP // Seperator ,.
+
+%token EQ // Equals =.
+%token DEQ // Double equals ==.
+
+%token EXPSEP // Expression seperator ;.
+
+%token<strval> WORD // Word, i.e. keyword.
+%token<fval> NUM // Number.
+
+%token SUB // Subtract -.
+%token ADD // Addition *.
+%token MUL // Multiplication *.
+%token DIV // Division /.
+
+%token NL // Newline.
+
+%token BACKSLASH
+
+%left ADD SUB
+%left MUL DIV
+%precedence NEG
+
+%type<ast> exp;
+%type<argarr> arg;
+%type<argarr> argstart;
+%type<exps> blockstart;
+%type<exps> block;
+%type<exps> inputstart
+%type<exps> input
+
+%start inputend // This makes no sense but w/e.
 
 %%
 
+inputstart:
+    exp {
+        DList* exps = dlist_init();
+        dlist_append(exps, $1);
+        $$ = exps;
+    }
+    ;
+
 input:
+    inputstart {
+        $$ = $1;
+    }
+    | input EXPSEP exp {
+        dlist_append($1, $3);
+        $$ = $1;
+    }
+    ;
+
+inputend:
     %empty
-    | exp { root = $1; }
+    | input {
+        root = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $1->buf, $1->ln));
+        dlist_destroypsv($1);
+    }
+    ;
+
+argstart:
+    exp {
+        ArgArr* argarr = argarr_init();
+        argarr_add(argarr, $1);
+        $$ = argarr;
+    }
+    ;
+
+arg:
+    argstart { $$ = $1; }
+    | arg SEP exp {
+        argarr_add($1, $3);
+        $$ = $1;
+    }
+    ;
+
+blockstart:
+    exp {
+        DList* exps = dlist_init(); // List of expressions.
+        dlist_append(exps, $1);
+        $$ = exps;
+    }
+    ;
+
+block:
+     blockstart { $$ = $1; }
+     | block EXPSEP exp {
+        dlist_append($1, $3);
+        $$ = $1;
+    }
     ;
 
 exp:
+    // Number.
     NUM { $$ = ast_init(AST_TYPE_NUM, ast_num_data_init($1)); }
-    | NEG NUM { $$ = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2)); }
-    | NUM PLUS NUM {
+
+    | BOOLT { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(1)); }
+    | BOOLF { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(0)); }
+
+    | exp DEQ exp {
         AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("+", 2, argv));
-    }
-    | NEG NUM PLUS NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("+", 2, argv));
-    }
-    | NUM NEG NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("-", 2, argv));
-    }
-    | NEG NUM NEG NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("-", 2, argv));
+        argv[0] = $1;
+        argv[1] = $3;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            2,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_eq))
+        ));
     }
 
-    | NUM MULT NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($3));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+    | IF exp exp exp {
+        AST** argv = calloc(3, sizeof(AST*));
+        argv[0] = $2;
+        argv[1] = $3;
+        argv[2] = $4;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            3,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_if))
+        ));
     }
-    | NEG NUM MULT NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init($4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
-    }
-    | NEG NUM MULT NEG NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$2));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$5));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
-    }
-    | NUM MULT NEG NUM {
-        AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init($1));
-        argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(-$4));
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init("*", 2, argv));
+    | IF exp exp ELSE exp {
+        AST** argv = calloc(3, sizeof(AST*));
+        argv[0] = $2;
+        argv[1] = $3;
+        argv[2] = $5;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            3,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_if))
+        ));
     }
 
+    // Variable reference.
+    | WORD {
+        $$ = ast_init(AST_TYPE_VREF, ast_vref_data_init($1));
+    }
+
+    // Call (general form).
+    | exp GROUPS arg GROUPE {
+        size_t argc = $3->ln;
+        AST** argv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $1
+        ));
+    }
+
+    // Call (convenient form).
+    | WORD GROUPS arg GROUPE {
+        size_t argc = $3->ln;
+        AST** argv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            ast_init(AST_TYPE_VREF, ast_vref_data_init($1))
+        ));
+    }
+
+    // Call (hacky convenient form).
+    | WORD GROUPS GROUPE {
+        size_t argc = 0;
+        AST** argv = NULL;
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            ast_init(AST_TYPE_VREF, ast_vref_data_init($1))
+        ));
+    }
+
+    // Function definitions. Convert to VDef of Lambda.
+    | WORD GROUPS arg GROUPE exp {
+        size_t parc = $3->ln;
+        AST** parv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init(
+            $1,
+            ast_init(AST_TYPE_LAMBDA, ast_lambda_data_init(
+                parc, parv, $5
+            ))
+        ));
+    }
+
+    // Lambda definitions.
+    | BACKSLASH GROUPS arg GROUPE exp {
+        size_t parc = $3->ln;
+        AST** parv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_LAMBDA, ast_lambda_data_init(parc, parv, $5));
+    }
+
+    // Block.
+    | BLOCKS block BLOCKE {
+        $$ = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $2->buf, $2->ln));
+    }
+
+    // Negative.
+    | SUB exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-1));
+        argv[1] = $2;
+        $$ = ast_init(AST_TYPE_CALL,
+            ast_call_data_init(
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF,
+                    ast_bif_data_init(builtin_mul)
+                )
+            )
+        );
+    }
+
+    // Group.
+    | GROUPS exp GROUPE { $$ = $2; }
+
+    // Variable definition.
+    | WORD EQ exp {
+        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init($1, $3));
+    }
+
+    | exp ADD exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = $1;
+        argv[1] = $3;
+        $$ = ast_init(AST_TYPE_CALL,
+            ast_call_data_init(
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_sum))
+            )
+        );
+    }
+
+    | exp SUB exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = $1;
+        argv[1] = $3;
+        $$ = ast_init(AST_TYPE_CALL,
+            ast_call_data_init(
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_sub))
+            )
+        );
+    }
+
+    | exp MUL exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = $1;
+        argv[1] = $3;
+        $$ = ast_init(AST_TYPE_CALL,
+            ast_call_data_init(
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_mul))
+            )
+        );
+    }
+
+    | exp DIV exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = $1;
+        argv[1] = $3;
+        $$ = ast_init(AST_TYPE_CALL,
+            ast_call_data_init(
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_div))
+            )
+        );
+    }
 %%

src/htab.c

@@ -0,0 +1,36 @@
+#include "include/htab.h"
+#include "include/fnv1a.h"
+#include "include/util.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+HTab* htab_init() {
+    HTab* htab = calloc(1, sizeof(HTab));
+
+    log_dbgf("HTAB %p", htab);
+
+    return htab;
+}
+
+void htab_destroy(HTab* htab) { free(htab); }
+
+// Get the index of a key.
+size_t geti(char* key) {
+    uint64_t hash = fnv1a_hash(key, strlen(key));
+    size_t i = hash & (HTAB_SPACE - 1); // Magic.
+    return i;
+}
+
+void* htab_get(HTab* htab, char* key) {
+    size_t i = geti(key);
+    log_dbgf("Getting something from hash table @ index %lu", i);
+    return (*htab)[i];
+}
+
+void htab_ins(HTab* htab, char* key, void* data) {
+    size_t i = geti(key);
+    (*htab)[i] = data;
+    log_dbgf("Inserted something to hash table @ index %lu", i);
+}

src/include/ast.h

@@ -1,38 +1,176 @@
 #ifndef AST_H
 #define AST_H
 
+#include "scope.h"
 #include <stdlib.h>
 
+// The type of an `AST`.
 typedef enum {
-    AST_TYPE_NUM,
-    AST_TYPE_CALL,
-    AST_TYPE_MAX = AST_TYPE_CALL
+    // Primitive types.
+    AST_TYPE_NUM,  // A number (float).
+    AST_TYPE_STR,  // A string
+    AST_TYPE_INT,  // An integer.
+    AST_TYPE_BOOL, // A boolean.
+    AST_TYPE_SYM,  // A symbol.
+    AST_TYPE_EXC,  // Exception.
+
+    // Collection types:
+    AST_TYPE_VEC,  // A vector (fixed size, fixed type).
+    AST_TYPE_LIST, // A list (variable size, variable type).
+
+    // Misc. types.
+    AST_TYPE_BIF,    // Built-in function.
+    AST_TYPE_CALL,   // A function call.
+    AST_TYPE_VDEF,   // A variable definition.
+    AST_TYPE_VREF,   // A variable reference.
+    AST_TYPE_BLOCK,  // A block of code (scope).
+    AST_TYPE_FDEF,   // A function definition.
+    AST_TYPE_LAMBDA, // An anonymous function definition.
+    AST_TYPE_ARG,    // A definition argument.
+    AST_TYPE_MAX = AST_TYPE_ARG,
 } ASTType;
 
+// An Abstract Syntax Tree.
 typedef struct {
-    ASTType type;
-    void* data;
+    ASTType type; // The type of the `AST`.
+    void* data;   // The data of the `AST`.
+    Scope* scope; // The scope of the `AST`.
 } AST;
 
+// Create a new `AST`.
 AST* ast_init(ASTType type, void* data);
+// Create a new `AST` with a specified scope.
+AST* ast_init_scope(ASTType type, void* data, Scope* scope);
+// Destroy an `AST`.
 void ast_destroy(AST* ast);
-void ast_print(AST* ast);
-void ast_print_i(AST* ast, int i);
 
+// A number.
 typedef double ASTNumData;
 
+// Create a new `ASTNumData`.
 ASTNumData* ast_num_data_init(double val);
+// Destroy an `ASTNumData`.
 void ast_num_data_destroy(ASTNumData* num);
-void ast_num_print(ASTNumData*, int i);
 
+// A boolean.
+typedef int ASTBoolData;
+
+// Create a new `ASTBoolData`.
+ASTBoolData* ast_bool_data_init(int val);
+// Destroy an `ASTBoolData`.
+void ast_bool_data_destroy(ASTBoolData* bol);
+
+// An exception.
+typedef struct ASTEXCDATA {
+    const char* msg; // The exception message.
+    AST* trace;      // The previous exception.
+} ASTExcData;
+// Create a new `ASTExecData. `msg` should be static.
+ASTExcData* ast_exc_data_init(const char* msg, AST* trace);
+// Destroy an `ASTExecData`.
+void ast_exc_data_destroy(ASTExcData* exc);
+
+// Argument list as anonymous struct.
+#define ARGS                                                                   \
+    struct {                                                                   \
+        size_t argc;                                                           \
+        AST** argv;                                                            \
+    }
+
+// Parameter list as anonymous struct.
+#define PARS                                                                   \
+    struct {                                                                   \
+        size_t parc;                                                           \
+        AST** parv;                                                            \
+    }
+
+// A built-in function.
+typedef AST* (*ASTBIFData)(size_t argc, AST** argv, Scope* scope);
+
+// Create a built-in function.
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*));
+// Destroy an `ASTBIFData`.
+void ast_bif_data_destroy(ASTBIFData* bif);
+
+// A lambda.
 typedef struct {
-    char* to;       // What the call's to.
-    size_t argc;    // Argument count.
-    AST** argv;     // Argument vector.
+    PARS;      // The parameters the lambda can accept.
+    AST* body; // The body expression to be executed.
+} ASTLambdaData;
+
+// Creates a new `ASTLambdaData`.
+ASTLambdaData* ast_lambda_data_init(size_t parc, AST** parv, AST* body);
+// Destroy an `ASTLambdaData`.
+void ast_lambda_data_destroy(ASTLambdaData*);
+
+// A call.
+typedef struct {
+    ARGS;     // The arguments the call is made with.
+    AST* exp; // The expression the call is to.
 } ASTCallData;
 
-ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv);
+// Create a new `ASTCallData`.
+ASTCallData* ast_call_data_init(size_t argc, AST** argv, AST* exp);
+// Destroy an `ASTCallData`.
 void ast_call_data_destroy(ASTCallData* call);
-void ast_call_print(ASTCallData*, int i);
+
+// A variable definition. Associates a name with an expression.
+typedef struct {
+    char* name;
+    AST* exp;
+} ASTVDefData;
+
+// Create a new `ASTVDefData`.
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp);
+// Destroy an `ASTVDefData`.
+void ast_vdef_data_destroy(ASTVDefData* vdef);
+
+// A variable reference.
+typedef struct {
+    char* to; // What the reference's to.
+} ASTVrefData;
+
+// Create a new `ASTVRefData`.
+ASTVrefData* ast_vref_data_init(char* to);
+// Destroy an `ASTVRefData`.
+void ast_vref_data_destroy(ASTVrefData* call);
+
+// A code block.
+typedef struct {
+    AST** inside; // What's inside the block.
+    size_t ln;    // How many ASTs are in the block.
+} ASTBlockData;
+
+// Create a new `ASTBlockData`.
+ASTBlockData* ast_block_data_init(AST** inside, size_t ln);
+// Destroy an `ASTBlockData`, recursively.
+void ast_block_data_destroy(ASTBlockData* block);
+// Destroy an `ASTBlockData`.
+void ast_block_data_destroy_psv(ASTBlockData* block);
+
+typedef struct {
+    char* name; // Function name.
+    ARGS;       // Function args.
+    AST* body;  // Function body.
+} ASTFDefData;
+
+// Create a new `ASTFDefData`.
+ASTFDefData* ast_fdef_data_init(char* name, size_t argc, AST** argv, AST* body);
+// Destroy an `ASTFDefData`, recursively.
+void ast_fdef_data_destroy(ASTFDefData* fdef);
+// Destroy an `ASTFDefData`.
+void ast_fdef_data_destroy_psv(ASTFDefData* fdef);
+
+typedef struct {
+    char* name; // Argument name.
+} ASTArgData;
+
+// Create a new `ASTArgData`.
+ASTArgData* ast_arg_data_init(char* name);
+// Destroy an `ASTArgData`.
+void ast_arg_data_destroy(ASTArgData* arg);
+
+// Find the expression associated with a name in the nearest scope.
+AST* ast_find(Scope* scope, char* name);
 
 #endif

src/include/ast_print.h

@@ -0,0 +1,44 @@
+#ifndef AST_PRINT_H
+#define AST_PRINT_H
+
+#include "ast.h"
+
+// Print an `AST`, recursively.
+void ast_print(AST* ast);
+// Helper function to `ast_print()`, where `i` is indentation level.
+void ast_print_i(AST* ast, int i);
+
+// Print an `ASTNumData`.
+void ast_num_print(ASTNumData*, int i);
+
+// Print an `ASTBoolData`.
+void ast_bool_print(ASTBoolData*, int i);
+
+// Print an `ASTExecData`.
+void ast_exc_print(ASTExcData*, int i);
+
+// Print an `ASTCallData`.
+void ast_call_print(ASTCallData*, int i);
+
+// Print an `ASTVDefData`.
+void ast_vdef_print(ASTVDefData*, int depth);
+
+// Print an `ASTVRefData`.
+void ast_vref_print(ASTVrefData*, int i);
+
+// Print an `ASTBlockData`.
+void ast_block_print(ASTBlockData*, int i);
+
+// Print an `ASTFDefData`.
+void ast_fdef_print(ASTFDefData* fdef, int i);
+
+// Print an `ASTArgData`.
+void ast_arg_print(ASTArgData* arg, int i);
+
+// Print an `ASTLambdaData`.
+void ast_lambda_print(ASTLambdaData* arg, int i);
+
+// Print an `ASTBIFData`.
+void ast_bif_print(ASTBIFData* arg, int i);
+
+#endif

src/include/builtin.h

@@ -0,0 +1,44 @@
+#ifndef BUILTIN_H
+#define BUILTIN_H
+
+#include "ast.h"
+#include <stddef.h>
+
+// Sum some nums.
+AST* builtin_sum(size_t argc, AST** argv, Scope* parent);
+
+// Subtract nums.
+AST* builtin_sub(size_t argc, AST** argv, Scope* parent);
+
+// Multiply nums.
+AST* builtin_mul(size_t argc, AST** argv, Scope* parent);
+
+// Divide nums.
+AST* builtin_div(size_t argc, AST** argv, Scope* parent);
+
+// Die.
+AST* builtin_die(size_t argc, AST** argv, Scope* parent);
+
+// If statement.
+AST* builtin_if(size_t argc, AST** argv, Scope* parent);
+
+// Equality.
+AST* builtin_eq(size_t argc, AST** argv, Scope* parent);
+
+struct builtin_data {
+    char* name;
+    AST* (*fn)(size_t argc, AST** argv, Scope* parent);
+};
+
+static struct builtin_data BUILTIN_FNS[] = {
+    { "sum", builtin_sum },
+    { "sub", builtin_sub },
+    { "mul", builtin_mul },
+    { "div", builtin_div },
+    { "die", builtin_die },
+    {"_if", builtin_if},
+    {"eq", builtin_eq},
+};
+#define BUILTIN_FNS_LN (arrln(BUILTIN_FNS))
+
+#endif

src/include/dlist.h

@@ -0,0 +1,24 @@
+#ifndef DLIST_H
+#define DLIST_H
+
+#include <stdlib.h>
+
+#define DLIST_INITSZ 128 * sizeof(void*)
+
+typedef struct {
+    void** buf; // The buffer containing the list.
+    size_t sz;  // The size of the buffer.
+    size_t ln;  // The number of elements in the list.
+} DList;
+
+// Create a new `DList`.
+DList* dlist_init(void);
+// Destroy a `DList`.
+void dlist_destroy(DList* dstr);
+// Destroy `DList` structure but preserve `->buf`.
+void dlist_destroypsv(DList* dstr);
+
+// Append `src` to `dest`.
+void dlist_append(DList* dest, void* src);
+
+#endif

src/include/dstr.h

@@ -6,18 +6,22 @@
 #define DSTR_INITSZ 128
 
 typedef struct {
-    char* buf;    // The buffer containing the string.
-    size_t bufsz; // The size of the buffer.
-    size_t ln;    // The number of characters in the buffer.
+    char* buf; // The buffer containing the string.
+    size_t sz; // The size of the buffer.
+    size_t ln; // The number of characters in the buffer.
 } Dstr;
 
+// Initialize a `DStr`.
 Dstr* dstr_init(void);
+// Destroy a `DStr`.
 void dstr_destroy(Dstr* dstr);
+// Destroy `DStr` structure but preserve `DStr->buf`.
+void dstr_destroypsv(Dstr* dstr);
 
-// Append ln characters of src to dest.
+// Append `ln` characters of `src` to `dest`.
 void dstr_append(Dstr* dest, char* src, size_t ln);
 
-// Append ch to dest.
+// Append `ch` to `dest`.
 void dstr_appendch(Dstr* dest, char ch);
 
 #endif

src/include/exec.h

@@ -2,9 +2,31 @@
 #define EXEC_H
 
 #include "ast.h"
+#include "scope.h"
 
-ASTNumData exec_expr(AST* ast);
-ASTNumData exec_call(AST* ast);
+// Start executing at the root of the AST. Initialize the `scope`.
+AST* exec_start(AST* ast);
+// Execute an expression. Delegates to the other executor functions.
+AST* exec_exp(AST* ast, Scope* parent);
+// Execute the expressions of a block.
+AST* exec_block(AST* ast, Scope* parent);
+// Execute a call.
+AST* exec_call(AST* ast, Scope* parent);
+// Execute a variable definition.
+AST* exec_vdef(AST* ast, Scope* parent);
+// Execute a variable reference.
+AST* exec_vref(AST* ast, Scope* parent);
+// Execute a function definition.
+AST* exec_fdef(AST* ast, Scope* parent);
+// Execute a lambda expression.
+AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent);
+// Print the result of an execution.
 void exec_print(double n);
 
+// Create a new scope and mark it as linked. Also update inherited scope.
+void exec_new_scope(AST* ast, Scope* inherit);
+
+// Inherit from another scope and mark it as linked.
+void exec_inherit_scope(AST* ast, Scope* inherit);
+
 #endif

src/include/fnv1a.h

@@ -0,0 +1,18 @@
+#ifndef FNV1A_H
+#define FNV1A_H
+
+// Implements the FNV-1a hash algorithm.
+
+#include <stdint.h>
+#include <stdlib.h>
+
+// FNV prime.
+#define FNV1A_PRIME_64 0x00000100000001b3u
+
+// Offset basis.
+#define FNV1A_BASIS_64 0xcbf29ce484222325u
+
+// Hash a string `str` of length `ln`.
+uint64_t fnv1a_hash(char* str, size_t ln);
+
+#endif

src/include/gc.h

@@ -0,0 +1,31 @@
+#ifndef GC_H
+#define GC_H
+
+#include <stdlib.h>
+
+// The type a GC can refer to.
+typedef enum {
+    GC_TYPE_AST,
+    GC_TYPE_SCOPE,
+    GC_TYPE_MAX = GC_TYPE_SCOPE
+} GCType;
+
+// Added to each AST and Scope; keep track of what's actually still accessible.
+typedef struct GC_STRUCT {
+    void* p;               // Pointer to the data.
+    struct GC_STRUCT* nxt; // The next GC in the linked list.
+    GCType type;           // What type of data.
+    bool marked;           // Whether the data is still accessible.
+} GC;
+
+GC* gc_init(void* p, GCType type, GC*);
+// Does not free ->p or ->nxt.
+void gc_destroy(GC* gc);
+
+// Allocate for an object in the heap, and keep track of it in the GC.
+void* gc_alloc(size_t sz, GCType type);
+
+// Free everything, immediately.
+void gc_hack_free();
+
+#endif

src/include/global.h

@@ -0,0 +1,4 @@
+#ifndef GLOBAL_H
+#define GLOBAL_H
+
+#endif

src/include/htab.h

@@ -0,0 +1,29 @@
+#ifndef HTAB_H
+#define HTAB_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define HTAB_FN fnv1a_hash // Function used for hashing.
+#define HTAB_SPACE                                                             \
+    1024 // Number of entries possible in the hash table; must be
+         // power of 2.
+
+// Hash Table.
+typedef void* HTab[HTAB_SPACE];
+
+// Create a new hash table.
+HTab* htab_init();
+// Destroy a hash table, but not its elements.
+void htab_destroy(HTab* htab);
+
+// Get element at `hash`. Return its contents, or NULL if nothing found.
+void* htab_get(HTab* htab, char* str);
+
+// Insert `data` at index `hash`.
+void htab_ins(HTab* htab, char* key, void* data);
+
+// Gets the length of the hash table.
+size_t htab_ln(HTab* htab);
+
+#endif

src/include/lexer.h

@@ -2,20 +2,29 @@
 #define LEXER_H
 
 #include <assert.h>
+#include <stddef.h>
+
+#include "ast.h"
+
+#define ARLN 8
+
+extern char* inp;
+
+typedef struct {
+    size_t sz;
+    size_t ln;
+    AST** buf;
+} ArgArr;
+
+ArgArr* argarr_init();
+void argarr_destroy(ArgArr* argarr);
+// Destroy ArgArr structure but preserve -> buf.
+void argarr_destroypsv(ArgArr* argarr);
+void argarr_add(ArgArr* argarr, AST* arg);
 
-#ifdef __has_include
-#if __has_include("../../build/grammars/grammar.tab.h")
 #include "../../build/grammars/grammar.tab.h"
-#else
-#warn "Build resources not present!"
-#endif
-#else
-#warn "Not sure whether build-time resources are present."
-#include "../../build/grammars/grammar.tab.h"
-#endif
 
 extern YYSTYPE yylval;
-extern char* inp;
 
 // Accumulate an integer.
 int acc_int(int c);

src/include/main.h

@@ -1,4 +1,2 @@
 // This file serves no purpose but because I've written my makefile this way it
 // has to exist for things to compile :P. TODO: Fix this.
-
-int four() { return 4; }

src/include/scope.h

@@ -0,0 +1,22 @@
+#ifndef SCOPE_H
+#define SCOPE_H
+
+#include "htab.h"
+
+// Represents the reverse linked tree of scope.
+typedef struct SCOPE_T {
+    HTab* here; // This scope's hash table.
+    struct SCOPE_T* inherit; // The scope to inherit from.
+    int uses; // How many `AST`s are linked to this scope. // TODO: REMOVE.
+} Scope;
+
+// Create a new `Scope`. Creates new empty `HTab` for current scope.
+Scope* scope_init(Scope* inherit);
+// Destroy all linked `Scope`s this inherits from.
+void scope_destroy(Scope* scope);
+// Destroy the current `Scope` only.
+void scope_destroy_psv(Scope *scope);
+// Insert a key/val pair into the `HTab` of a `Scope`.
+void scope_add(Scope* scope, char* key, void* val);
+
+#endif

src/include/stack.h

@@ -6,18 +6,19 @@
 #define STACK_MAX 64
 
 typedef struct {
-    size_t i;               // Current index in the stack.
-    void* val[STACK_MAX];   // The stack itself.
+    size_t ln;            // The length of the stack (i.e., how many elements).
+    void* buf[STACK_MAX]; // The stack itself.
 } Stack;
 
+// Create a `Stack`.
 Stack* stack_init();
-// Destroy a stack.
-// Note that `stack->i` must be `0`.
+// Destroy a `Stack`.
+// Note that `->i` must be `0`, i.e. the `Stack` must be empty.
 void stack_destroy(Stack* stack);
 
-// Push a value to the stack.
+// Push a value to the `Stack`.
 void stack_push(Stack* stack, void* val);
-// Pop a value from the stack.
+// Pop a value from the `Stack`.
 void* stack_pop(Stack* stack);
 
 #endif

src/include/util.h

@@ -1,17 +1,35 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#include <signal.h>
+
+// Most of this file is cursed printing macros for `ast_print()`. Do not attempt
+// to comprehend.
+
+// Allocate a pointer with a type.
+#define talloc(T, X) T* X = malloc(sizeof(T));
+
+// Get the length of an array.
+#define arrln(A) (sizeof(A)/sizeof(*A))
+
+// Trap GDB &c.
+#define TRAP() RAISE(SIGTRAP)
+
 #ifdef DBG // Debug macros
 
 // Log a message.
 #define log_dbg(msg)                                                           \
-    printf("\033[37;1mdbg\033[0m:\033[37m%s\033[0m:\033[32m " msg "\033[0m\n", \
-           __func__);
+    printf(                                                                    \
+        "\033[37;1mdbg\033[0m:\033[37m%s\033[0m:\033[32m " msg "\033[0m\n",    \
+        __func__                                                               \
+    );
 
 // Log a message with formatting.
 #define log_dbgf(msg, ...)                                                     \
-    printf("\033[37;1mdbg\033[0m:\033[37m%s\033[0m:\033[32m " msg "\033[0m\n", \
-           __func__, __VA_ARGS__);
+    printf(                                                                    \
+        "\033[37;1mdbg\033[0m:\033[37m%s\033[0m:\033[32m " msg "\033[0m\n",    \
+        __func__, __VA_ARGS__                                                  \
+    );
 
 #else // ifdef DBG
 #define log_dbg(msg)
@@ -50,23 +68,30 @@
 
 // Print & indent the title of a section.
 #define INDENT_TITLE(THING, WHERE)                                             \
-    printf("%s" COL_BCYA THING COL_RESET " @" COL_MAG " %p\n" COL_RESET, INDENT_spacing->buf, WHERE);
+    printf(                                                                    \
+        "%s" COL_BCYA THING COL_RESET " @" COL_MAG " %p\n" COL_RESET,          \
+        INDENT_spacing->buf, WHERE                                             \
+    );
 
 // Print & indent a thing.
 #define INDENT_FIELD(FIELD, VAL, ...)                                          \
-    printf("%s " COL_BWHI FIELD ": " COL_RESET COL_WHI VAL COL_RESET "\n",     \
-           INDENT_spacing->buf, __VA_ARGS__);
+    printf(                                                                    \
+        "%s " COL_BWHI FIELD ": " COL_RESET COL_WHI VAL COL_RESET "\n",        \
+        INDENT_spacing->buf, __VA_ARGS__                                       \
+    );
 
 // Print & indent a thing with a newline before the val.
 #define INDENT_FIELD_NL(FIELD, VAL, ...)                                       \
-    printf("%s " COL_BWHI FIELD ":" COL_RESET "\n %s " COL_WHI VAL COL_RESET   \
-           "\n",                                                               \
-           INDENT_spacing->buf, INDENT_spacing->buf, __VA_ARGS__);
+    printf(                                                                    \
+        "%s " COL_BWHI FIELD ":" COL_RESET "\n %s " COL_WHI VAL COL_RESET      \
+        "\n",                                                                  \
+        INDENT_spacing->buf, INDENT_spacing->buf, __VA_ARGS__                  \
+    );
 
 // Print & indent a thing without any newline.
-#define INDENT_FIELD_EXT_NONL_START(FIELD)                                         \
+#define INDENT_FIELD_EXT_NONL_START(FIELD)                                     \
     printf("%s " COL_BWHI FIELD ":\n" COL_RESET COL_WHI, INDENT_spacing->buf);
-#define INDENT_FIELD_NONL_END printf( "\n" COL_RESET);
+#define INDENT_FIELD_NONL_END printf("\n" COL_RESET);
 
 // Print an array A of N things, by calling the function F.
 #define INDENT_FIELD_LIST(FIELD, A, N, F)                                      \
@@ -77,9 +102,14 @@
     printf(COL_BWHI "%s ]\n" COL_RESET, INDENT_spacing->buf);
 
 // End an indent block.
-#define INDENT_END printf(COL_RESET); dstr_destroy(INDENT_spacing);
+#define INDENT_END                                                             \
+    printf(COL_RESET);                                                         \
+    dstr_destroy(INDENT_spacing);
 
-// Allocate a pointer with a type.
-#define talloc(T, X) T* X = malloc(sizeof(T));
+#define INDENT_FIELD_LIST_OPEN(FIELD)                                          \
+    printf("%s " COL_BWHI FIELD ": [\n" COL_RESET, INDENT_spacing->buf);
+
+#define INDENT_FIELD_LIST_CLOSE                                                \
+    printf(COL_BWHI "%s ]\n" COL_RESET, INDENT_spacing->buf);
 
 #endif

src/lexer.c

@@ -1,9 +1,43 @@
+#include <complex.h>
 #include <ctype.h>
 #include <limits.h>
 #include <math.h>
 #include <stdio.h>
+#include <string.h>
 
+#include "include/dstr.h"
 #include "include/lexer.h"
+#include "include/util.h"
+
+ArgArr* argarr_init() {
+    ArgArr* argarr = malloc(sizeof(ArgArr));
+
+    argarr->sz = ARLN * sizeof(AST*);
+    argarr->ln = 0;
+    argarr->buf = malloc(argarr->sz);
+
+    return argarr;
+}
+
+void argarr_destroy(ArgArr* argarr) {
+    free(argarr->buf);
+    free(argarr);
+}
+
+void argarr_destroypsv(ArgArr* argarr) { free(argarr); }
+
+void argarr_add(ArgArr* argarr, AST* arg) {
+    if ((argarr->ln + 1) * sizeof(AST*) > argarr->sz) {
+        argarr->sz *= 2;
+        argarr->buf = realloc(argarr->buf, argarr->sz);
+        log_dbgf(
+            "ArgArr @ %p doubled from %ld to %ld", argarr, argarr->sz / 2,
+            argarr->sz
+        );
+    }
+
+    argarr->buf[argarr->ln++] = arg;
+}
 
 int acc_int(int c) {
     int value = c - '0';
@@ -28,30 +62,46 @@ double acc_float(int c) {
         inp++;
 
         while (isdigit(*inp)) {
-            // TODO:
-            // Accumulate as int, divide once at end.
-            // value = value + (((double)(*inp - '0'))/pow(10.0l,
-            // (double)(inp-oinp))); // Accumulate value.
             value = value * 10 + (*inp - '0'); // Accumulate value.
             dplaces++;
             inp++;
         }
         value = value / pow(10, dplaces);
     }
-
-    // > 1.20000
-    // = 1.0 + 2/10
-
-    // > 1.23
-    // = 1.2 + 3/100
     return value;
 }
 
+char* acc_word(int c) {
+    Dstr* val = dstr_init();
+    while (isalpha(*inp) || *inp == '_') {
+        dstr_appendch(val, *(inp - 1));
+        inp++;
+    }
+    dstr_appendch(val, *(inp - 1));
+
+    char* ret = val->buf;
+    dstr_destroypsv(val);
+    return ret;
+}
+
+char* acc_deq(int c) {
+    Dstr* val = dstr_init();
+    while (*inp == '=') {
+        dstr_appendch(val, *(inp - 1));
+        inp++;
+    }
+    dstr_appendch(val, *(inp - 1));
+
+    char* ret = val->buf;
+    dstr_destroypsv(val);
+    return ret;
+}
+
 int yylex() {
     if (*inp == '\0') return YYEOF;
 
     // Skip all whitespace.
-    while (*inp == ' ' || *inp == '\t') { inp++; }
+    while (*inp == ' ' || *inp == '\t') inp++;
 
     // Assign & consume current character.
     int c = *inp++;
@@ -62,15 +112,43 @@ int yylex() {
         return NUM;
     }
 
-    switch (c) {
-        case '+':  return PLUS;
-        case '\n': return NL;
-        case '-':  return NEG;
-        case '*':  return MULT;
-        default:   return CALL;
+    if (c == '=') {
+        yylval.strval = acc_deq(c);
+        if (!strcmp(yylval.strval, "=")) return EQ;
+        if (!strcmp(yylval.strval, "==")) return DEQ;
     }
 
-    fprintf(stderr, "Unexpected character: %c\n", c);
+    if (isalpha(c) || c == '_') {
+        yylval.strval = acc_word(c);
+
+        if (!strcmp(yylval.strval, "TRUE") || !strcmp(yylval.strval, "T"))
+            return BOOLT;
+        if (!strcmp(yylval.strval, "FALSE") || !strcmp(yylval.strval, "F"))
+            return BOOLF;
+        if (!strcmp(yylval.strval, "if")) return IF;
+        if (!strcmp(yylval.strval, "else")) return ELSE;
+
+        return WORD;
+    }
+
+    switch (c) {
+        case '+':  return ADD;
+        case '\n': return NL;
+        case '-':  return SUB;
+        case '*':  return MUL;
+        case '/':  return DIV;
+        case '(':  return GROUPS;
+        case ')':  return GROUPE;
+        case ',':  return SEP;
+        case ';':  return EXPSEP;
+        case '{':  return BLOCKS;
+        case '}':  return BLOCKE;
+        // case '=':  return EQ;
+        case '\\': return BACKSLASH;
+        case '?':  return IF;
+        case ':':  return ELSE;
+        default:   fprintf(stderr, "Unexpected character: %c\n", c);
+    }
 
     return 0;
 }

src/main.c

@@ -1,8 +1,11 @@
 #include <stdio.h>
+#include <string.h>
 
 #include "include/ast.h"
+#include "include/ast_print.h"
 #include "include/dstr.h"
 #include "include/exec.h"
+#include "include/gc.h"
 #include "include/lexer.h"
 #include "include/util.h"
 
@@ -10,14 +13,22 @@
 
 // Global Abstract Syntax Tree.
 extern AST* root;
-
-// Global input text.
-char* inp = NULL;
-
+extern char* inp;
 extern int yyparse();
 
 int main(int argc, char** argv) {
 
+    if (argc - 1 && strlen(argv[1]) > 0 && (inp = argv[1]) && !yyparse()) {
+        log_dbg("Parsed successfully!\n");
+        ast_print(root);
+        AST* eval = exec_start(root);
+        ast_print(eval);
+        // ast_destroy(eval);
+        // ast_destroy(root);
+        gc_hack_free();
+        exit(0);
+    }
+
     while (1) {
         Dstr* ln = dstr_init();
         char c;
@@ -31,7 +42,7 @@ int main(int argc, char** argv) {
             switch (c) {
                 case EOF:  dstr_destroy(ln); goto lnskip;
                 case '\n': goto lnend;
-                default:   dstr_appendch(ln, c); log_dbgf("cchar: %c", c);
+                default:   dstr_appendch(ln, c);
             }
         } while (1);
 
@@ -45,13 +56,25 @@ int main(int argc, char** argv) {
                 log_dbg("Parsed successfully!\n");
             } else printf("Parse error.\n");
 
-            exec_print(exec_expr(root));
 #ifdef DBG
             ast_print(root);
 #endif
+
+            AST* eval = exec_start(root);
+            ast_print(eval);
+            // Awful hack to exit when die() is called, until proper exception
+            // handling is implemented. TODO TODO TODO PLSFIX.
+            if (eval->type == AST_TYPE_EXC &&
+                ((ASTExcData*)eval->data)->msg[0] == '8') {
+                gc_hack_free();
+                exit(1);
+            }
+            gc_hack_free();
         }
 
         dstr_destroy(ln);
     }
 lnskip:;
+
+    return 0;
 }

src/scope.c

@@ -0,0 +1,37 @@
+#include "include/scope.h"
+#include "include/gc.h"
+#include "include/htab.h"
+#include "include/util.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+Scope* scope_init(Scope* inherit) {
+    Scope* scope = gc_alloc(sizeof(Scope), GC_TYPE_SCOPE);
+
+    scope->here = htab_init();
+    scope->inherit = inherit;
+    scope->uses = 0;
+
+    log_dbgf("%p: new scope, inherits from %p", scope, inherit);
+
+    return scope;
+}
+
+void scope_destroy(Scope* scope) {
+    if (!scope) return;
+    htab_destroy(scope->here);
+    if (scope->inherit != NULL) scope_destroy(scope->inherit);
+    free(scope);
+}
+
+void scope_destroy_psv(Scope* scope) {
+    if (!scope) return;
+    log_dbgf("%p: destroying", scope);
+    htab_destroy(scope->here);
+    scope->inherit = NULL;
+    free(scope);
+}
+
+inline void scope_add(Scope* scope, char* key, void* val) {
+    htab_ins(scope->here, key, val);
+}

src/stack.c

@@ -1,5 +1,5 @@
 #include <assert.h>
-#include <stdio.h>
+#include <stdio.h> // IWYU pragma: keep. Req by util macros.
 #include <string.h>
 
 #include "include/stack.h"
@@ -8,33 +8,34 @@
 Stack* stack_init() {
     talloc(Stack, stack);
 
-    memset(stack->val, 0, sizeof(void*) * STACK_MAX);
-    stack->i = 0;
+    memset(stack->buf, 0, sizeof(void*) * STACK_MAX);
+    stack->ln = 0;
 
     return stack;
 }
 
 void stack_destroy(Stack* stack) {
     // Can only free an empty stack.
-    assert(stack->i == 0);
+    assert(stack->ln == 0);
     free(stack);
 }
 
 void stack_push(Stack* stack, void* val) {
-    if (stack->i >= STACK_MAX) {
+    if (stack->ln >= STACK_MAX) {
         log_dbgf("Ran out of stack (max: %d)", STACK_MAX);
         return;
     }
 
-    stack->val[stack->i] = val;
-    stack->i++;
+    stack->buf[stack->ln] = val;
+    stack->ln++;
+    log_dbgf("pushed to stack, inc ln to %ld", stack->ln);
 }
 
 void* stack_pop(Stack* stack) {
-    if (stack->i <= 0) {
+    if (stack->ln <= 0) {
         log_dbg("Can't pop empty stack.");
         return (void*)-1;
     }
 
-    return stack->val[--stack->i];
+    return stack->buf[--stack->ln];
 }

test/test_ast.c

@@ -0,0 +1,59 @@
+#include "../src/include/ast.h"
+#include "Unity/src/unity.h"
+#include "Unity/src/unity_internals.h"
+#include <string.h>
+
+void setUp() {}
+void tearDown() {}
+
+void test_ast_num() {
+    ASTNumData* num = ast_num_data_init(12.0);
+    AST* ast = ast_init(AST_TYPE_NUM, num);
+
+    TEST_ASSERT_EQUAL(AST_TYPE_NUM, ast->type);
+    TEST_ASSERT_EQUAL(12.0, *(ASTNumData*)ast->data);
+
+    ast_destroy(ast);
+}
+
+void test_ast_call() {
+    AST** argv = malloc(2*sizeof(AST*));
+    argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(1.0));
+    argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(2.0));
+
+    char* name = malloc(2);
+    strcpy(name, "f");
+
+    ASTCallData* call = ast_call_data_init(name, 2, argv);
+
+    AST* ast = ast_init(AST_TYPE_CALL, call);
+
+    TEST_ASSERT_EQUAL(AST_TYPE_CALL, ast->type);
+    TEST_ASSERT_EQUAL(name, ((ASTCallData*)ast->data)->to);
+    TEST_ASSERT_EQUAL(2, ((ASTCallData*)ast->data)->argc);
+    TEST_ASSERT_EQUAL(1.0, ((ASTCallData*)ast->data)->argv[0]);
+    TEST_ASSERT_EQUAL(2.0, ((ASTCallData*)ast->data)->argv[1]);
+
+    ast_destroy(ast);
+}
+
+void test_ast_vref() {
+    char* s = malloc(2);
+    strcpy(s, "x");
+    ASTVrefData* vref = ast_vref_data_init(s);
+    AST* ast = ast_init(AST_TYPE_VREF, vref);
+
+    TEST_ASSERT_EQUAL(AST_TYPE_VREF, ast->type);
+    ASTVrefData data = *(ASTVrefData*)ast->data;
+    TEST_ASSERT_EQUAL_STRING("x", data.to);
+
+    //ast_destroy(ast);
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_ast_num);
+    //RUN_TEST(test_ast_call);
+    //RUN_TEST(test_ast_vref);
+    return UNITY_END();
+}

test/test_dlist.c

@@ -0,0 +1,41 @@
+#include "../src/include/dlist.h"
+#include "Unity/src/unity.h"
+
+void setUp() {};
+void tearDown() {};
+
+void test_dlist_init() {
+    DList* dlist = dlist_init();
+    TEST_ASSERT_EQUAL(0, dlist->ln);
+    TEST_ASSERT_EQUAL(DLIST_INITSZ, dlist->sz);
+}
+
+void test_dlist_append() {
+    DList* dlist;
+
+    // Test simple appending.
+    dlist = dlist_init();
+    int* n = malloc(sizeof(int));
+    *n = 1;
+    dlist_append(dlist, n);
+
+    TEST_ASSERT_EQUAL(n, dlist->buf[0]);
+    TEST_ASSERT_EQUAL(1, dlist->ln);
+
+    dlist_destroy(dlist);
+
+    // Test buffer doubling.
+    dlist = dlist_init();
+
+    for (int i = 0; i < 129; i++) dlist_append(dlist, &i);
+
+    TEST_ASSERT_EQUAL(129, dlist->ln);
+    TEST_ASSERT_EQUAL(DLIST_INITSZ*2, dlist->sz);
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_dlist_init);
+    RUN_TEST(test_dlist_append);
+    return UNITY_END();
+}

test/test_dstr.c

@@ -0,0 +1,78 @@
+#include "../src/include/dstr.h"
+#include "Unity/src/unity.h"
+#include <string.h>
+
+void setUp() {};
+void tearDown() {};
+
+void test_dstr_init() {
+    Dstr* dstr = dstr_init();
+    TEST_ASSERT_EQUAL(0, strlen(dstr->buf));
+    TEST_ASSERT_EQUAL(0, dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->sz);
+}
+
+void test_dstr_append() {
+    Dstr* dstr;
+
+    // Test simple appending.
+    dstr = dstr_init();
+    char* hello_world = "Hello, world!";
+    dstr_append(dstr, hello_world, strlen(hello_world));
+
+    TEST_ASSERT_EQUAL_STRING(hello_world, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(hello_world), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->sz);
+
+    dstr_destroy(dstr);
+
+    // Test buffer doubling.
+    dstr = dstr_init();
+
+    char h[DSTR_INITSZ + 20];
+    memset(h, 'h', DSTR_INITSZ + 19);
+    h[DSTR_INITSZ + 19] = '\0';
+    dstr_append(dstr, h, strlen(h));
+
+    TEST_ASSERT_EQUAL_STRING(h, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(h), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ * 2, dstr->sz);
+}
+
+void test_dstr_appendch() {
+    Dstr* dstr;
+
+    // Test simple character appending.
+    dstr = dstr_init();
+    char c = 'c';
+    char* c_str = "c";
+    dstr_appendch(dstr, c);
+
+    TEST_ASSERT_EQUAL_STRING(c_str, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(c_str), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->sz);
+
+    dstr_destroy(dstr);
+
+    // Test buffer doubling.
+    dstr = dstr_init();
+
+    // Test against this string.
+    char h[DSTR_INITSZ + 20];
+    memset(h, 'h', DSTR_INITSZ + 19);
+    h[DSTR_INITSZ + 19] = '\0';
+
+    for (int i = 0; i < DSTR_INITSZ + 19; i++) dstr_appendch(dstr, 'h');
+
+    TEST_ASSERT_EQUAL_STRING(h, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(h), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ * 2, dstr->sz);
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_dstr_init);
+    RUN_TEST(test_dstr_append);
+    RUN_TEST(test_dstr_appendch);
+    return UNITY_END();
+}

test/test_htab.c

@@ -0,0 +1,27 @@
+#include "../src/include/htab.h"
+#include "Unity/src/unity.h"
+#include "Unity/src/unity_internals.h"
+#include <string.h>
+
+void setUp() {}
+void tearDown() {}
+
+void test_htab() {
+    char* key = "hello";
+    char* data = "world";
+
+    HTab* htab = htab_init();
+
+    htab_ins(htab, key, data);
+
+    TEST_ASSERT_EQUAL_STRING(data, htab_get(htab, key));
+    TEST_ASSERT_NOT_EQUAL(data, htab_get(htab, "h"));
+}
+
+int main() {
+    UNITY_BEGIN();
+
+    RUN_TEST(test_htab);
+
+    return UNITY_END();
+}

test/val/test.bats

@@ -0,0 +1,131 @@
+#!/usr/bin/env bats
+
+bin() { ./scl.out $1 | tail -n1; }
+
+@test "simple addition" {
+    run bin "1+1"
+    [ "$output" = "= 2.000000" ]
+
+    run bin "-1+1"
+    echo $output
+    [ "$output" = "= 0.000000" ]
+
+    run bin "1+-1"
+    [ "$output" = "= 0.000000" ]
+
+    run bin "-1+-1"
+    [ "$output" = "= -2.000000" ]
+}
+
+@test "simple subtraction" {
+    run bin "1-1"
+    [ "$output" = "= 0.000000" ]
+
+    run bin "-1-1"
+    [ "$output" = "= -2.000000" ]
+
+    run bin "1--1"
+    [ "$output" = "= 2.000000" ]
+
+    run bin "-1--1"
+    [ "$output" = "= 0.000000" ]
+}
+
+@test "simple multiplication" {
+    run bin "1*2"
+    [ "$output" = "= 2.000000" ]
+
+    run bin "-1*2"
+    [ "$output" = "= -2.000000" ]
+
+    run bin "1*-1"
+    [ "$output" = "= -1.000000" ]
+
+    run bin "-1*-1"
+    [ "$output" = "= 1.000000" ]
+}
+
+@test "simple division" {
+    run bin "1/2"
+    [ "$output" = "= 0.500000" ]
+
+    run bin "-1/2"
+    [ "$output" = "= -0.500000" ]
+
+    run bin "1/-1"
+    [ "$output" = "= -1.000000" ]
+
+    run bin "-1/-1"
+    [ "$output" = "= 1.000000" ]
+}
+
+@test "order of operations" {
+    run bin "1+2*3"
+    [ "$output" = "= 7.000000" ]
+
+    run bin "2*3+1"
+    [ "$output" = "= 7.000000" ]
+
+    run bin "6/2-1"
+    [ "$output" = "= 2.000000" ]
+
+    run bin "1-6/2"
+    [ "$output" = "= -2.000000" ]
+}
+
+@test "order of operations with parenthesis" {
+    run bin "(1+2)*3"
+    [ "$output" = "= 9.000000" ]
+
+    run bin "-(1+2*3)"
+    [ "$output" = "= -7.000000" ]
+
+    run bin "-(-(1+2)*3)"
+    [ "$output" = "= 9.000000" ]
+}
+
+@test "basic blocks" {
+    run bin "{1}"
+    [ "$output" = "= 1.000000" ]
+
+    run bin "2+{3;4}"
+    [ "$output" = "= 6.000000" ]
+
+    run bin "5*{1+1;5*2}"
+    echo $output
+    [ "$output" = "= 50.000000" ]
+}
+
+@test "variable definition" {
+    run bin "x=1"
+    [ "$output" = "= 1.000000" ]
+
+    run bin "x=1;x+1"
+    [ "$output" = "= 2.000000" ]
+
+    run bin "h=7;j=2;k=8;l=4;h*h-l+j*k"
+    echo $output
+    [ "$output" = "= 61.000000" ]
+}
+
+#@test "function definition" {
+#    run bin "f(n)=2*n; f(2)"
+#    [ "$output" = "= 4.000000" ]
+#}
+
+@test "type stuff" {
+    run bin "x:int=1"
+    [ "$output" = "= 1" ]
+
+    run bin "x=1.5; type(x)"
+    [ "$output" = "= num"]
+
+    run bin "x:int=1.5; type(x)"
+    [ "$output" = "= int" ]
+
+    run bin "x:int=1.5"
+    [ "$output" = "= 1" ]
+
+    run bin "print(\"Hello, world!\")"
+    [ "$output" = "= Hello, world!" ]
+}

type-notes.md

@@ -0,0 +1,21 @@
+Primitive Types
+- num
+- bool
+- str
+
+```
+fact(x) = ? (x <= 1) 1 : f(x-1) * x
+> lambda
+fact(5) == 120
+> True
+```
+
+Ordered collections.
+| Name | Homogeneous | Fixed Size | Unique |
+|---|---|---|---|
+| Collection | No | No | No |
+| List |  Yes | No | No |
+| Array | Yes | Yes | No |
+| Group | No | Yes | No |
+| Set | Yes | No | Yes |
+| Perm | Yes | Yes | Yes |