Updated README.md.

NOTE: changed versioning system slightly.

README.md

@@ -1,20 +1,20 @@
 # SCL: Simple CAS Language
 
-Version v1.0-alpha
+*v0.3*
 
 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 basic 4-function calculator with order
-of operations and local variables. The codebase is about 1,400 lines of C,
-including a parser, interpreter, and runtime. It uses a linked environment
-scoping model.
+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
+handwritten C, including a parser, interpreter, and runtime. It uses a linked
+environment scoping model.
 
 ## Usage
 
 To download and run:
 
 ```bash
-git clone https://git.signorovitch.org/jacob/scl -b stable && cd scl
+git clone https://git.signorovitch.org/scl/scl -b stable && cd scl
 make release
 ./scl.out
 ```
@@ -22,75 +22,44 @@ make release
 ### For Development
 
 ```bash
-git clone git@signorovitch.org:jacob/scl --recurse-submodules && cd scl
+git clone git@signorovitch.org:scl/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.
+*Note that tests are currently in poor use. I hope to amend this in the future.*
 
 ## Syntax
 
-As one would expect, you can evaluate simple infix expressions:
+SCL's syntax will feel familiar to other functional programming languages.
 
 ```scl
-> 1 + 1
+> x = 3 + 3 * 3; x + 1
+= 13
+> f(x) x + 1
+> f(1)
 = 2
-```
-
-You can also define your own functions and variables:
-
-```scl
-> f(x) = 2x
-> n = 3
-> f(n)
-= 6
-```
-
-As SCL uses a linked environment model for scope, arguments are passed by
-reference by default. If you would like to pass by value (i.e., a copy) you may
-use the syntax:
-
-```scl
-> f(x) = x = 1
-> n = 4
-> f($n) # Pass a copy of n.
-= 1
-> n
+> (\(x) 2 * x)(5)
+= 10
+> f(g) g(2)
+> f(\(x) 2 * x)
 = 4
-> f(n) # Pass a reference to n.
-= 1
-> n
-> 1
 ```
 
-Symbolic algebra is done in the following manner:
+Here's a simple factorial function, using recursion:
 
 ```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:
+SCL's syntax is quite flexible. The above function could be more concisely
+written as:
 
 ```scl
-> f(x: int): int = 2x
-> f(3)
-= 6
-> f(3.1)
-! Traceback:
-! In call to `f(x: int): int`:
-! TypeError (58): Argument `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

@@ -12,10 +12,10 @@
   - [x] Order of operations
   - [x] Parse function application
   - [x] Parse order of operations with parenthesis
-  - [ ] Parse variable invocation
+  - [x] Parse variable invocation
   - [x] Parse variable definition
     - [ ] Parse types
-  - [ ] Parse function definition
+  - [x] Parse function definition
   - [ ] Parse lists/arrays/vectors
   - [x] Parse blocks
   - [ ] Parse control flow
@@ -32,9 +32,9 @@
 
 - [ ] Executer
   - [x] Exec function calls
-  - [ ] Exec variable use
-  - [ ] Exec variable definition
-  - [ ] Exec function definition
+  - [x] Exec variable use
+  - [x] Exec variable definition
+  - [x] Exec function definition
   - [ ] Exec symbolic variables
   - [ ] Exec control flow statements
   - [ ] Exec variadic functions

TODO.md

@@ -1,7 +1,9 @@
-0. Create file to describe properties of terminology used; param, arg, var, &c.
-1. Differenciate parameters and arguments -- params for function definitions,
-arguments for function calls
-2. Add scope field to all ASTs, and new scope layer for those that need it.
+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

@@ -11,7 +11,7 @@ TEST_DIR = test
 TEST_BUILD_DIR = $(BUILD_DIR)/test
 TEST_OBJ_DIR = $(TEST_BUILD_DIR)/obj
 
-CC = clang -std=c2x
+CC = clang -std=c23
 LINK = clang
 CFLAGS = -Wall -DDBG -ggdb -fsanitize=leak
 LDFLAGS = -lm

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

@@ -1,3 +1,2 @@
-f(n) = 2 * n
-
-f(5)
+apply(f, x) f(x)
+apply(\(x) x + 1, 2)

src/ast.c

@@ -1,34 +1,31 @@
+#include <inttypes.h>
 #include <stdio.h>
 
 #include "include/ast.h"
-#include "include/dstr.h"
-#include "include/htab.h"
+#include "include/gc.h"
+#include "include/scope.h"
 #include "include/util.h"
 
 extern AST* root;
 
-static char* asttype_names[] = {
-    [AST_TYPE_CALL] = "FUNC CALL",
-    [AST_TYPE_NUM] = "NUMBER",
-    [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* ast_init(ASTType type, void* data) {
-    AST* ast = malloc(sizeof(AST));
+    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, HTab* scope) {
+AST* ast_init_scope(ASTType type, void* data, Scope* scope) {
     AST* ast = malloc(sizeof(AST));
 
     ast->type = type;
@@ -42,45 +39,22 @@ 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_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(ast->data); break;
-        case AST_TYPE_FDEF:  ast_fdef_data_destroy(ast->data); break;
-        case AST_TYPE_ARG:   ast_arg_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);
     }
 
     free(ast);
-    htab_destroy(ast->scope);
-}
-
-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("scope", "%p", ast->scope);
-    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;
-        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;
-        default:             exit(1);
-    }
-    INDENT_FIELD_NONL_END;
-    INDENT_END;
 }
 
 ASTNumData* ast_num_data_init(double val) {
@@ -93,46 +67,57 @@ ASTNumData* ast_num_data_init(double val) {
 
 void ast_num_data_destroy(ASTNumData* num) { free(num); }
 
-void ast_num_print(ASTNumData* data, int i) {
-    INDENT_BEGIN(i);
+ASTBoolData* ast_bool_data_init(int val) {
+    talloc(ASTBoolData, bol);
 
-    INDENT_FIELD("data", "%lf", *data);
+    *bol = val;
 
-    INDENT_END;
+    return bol;
 }
 
-ASTExcData* ast_exc_data_init(char* msg, AST* trace) {
+void ast_bool_data_destroy(ASTBoolData* bol) { free(bol); }
+
+ASTExcData* ast_exc_data_init(const char* msg, AST* trace) {
     ASTExcData* data = malloc(sizeof(ASTExcData));
     data->msg = msg;
     data->trace = trace;
     return data;
 }
 
-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_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**)) {
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*)) {
     return (ASTBIFData*)fn;
 }
 
-ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv) {
+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;
 
@@ -141,49 +126,27 @@ 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++) ast_destroy(call->argv[i]);
     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);
-
-    INDENT_END;
-}
-
-ASTVDefData* ast_vdef_data_init(char* name, AST* val) {
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp) {
     talloc(ASTVDefData, vdef);
 
     vdef->name = name;
-    vdef->val = val;
+    vdef->exp = exp;
 
     return vdef;
 }
 
 void ast_vdef_data_destroy(ASTVDefData* vdef) {
-    ast_destroy(vdef->val);
     free(vdef->name);
     free(vdef);
 }
 
-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("val");
-    ast_print_i(vdef->val, depth + 2); // 2 because already indented.
-    INDENT_FIELD_NONL_END;
-
-    INDENT_END;
-}
+// VRef.
 
 ASTVrefData* ast_vref_data_init(char* to) {
     talloc(ASTVrefData, vref);
@@ -198,15 +161,6 @@ void ast_vref_data_destroy(ASTVrefData* vref) {
     free(vref);
 }
 
-void ast_vref_print(ASTVrefData* data, int i) {
-    INDENT_BEGIN(i);
-
-    INDENT_TITLE("ASTVrefData", data);
-    INDENT_FIELD("to", "%s", data->to);
-
-    INDENT_END;
-}
-
 ASTBlockData* ast_block_data_init(AST** inside, size_t ln) {
     ASTBlockData* block = malloc(sizeof(ASTBlockData));
 
@@ -223,14 +177,9 @@ void ast_block_data_destroy(ASTBlockData* block) {
     free(block);
 }
 
-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_block_data_destroy_psv(ASTBlockData* block) {
+    free(block->inside);
+    free(block);
 }
 
 ASTFDefData*
@@ -251,15 +200,10 @@ void ast_fdef_data_destroy(ASTFDefData* fdef) {
     ast_destroy(fdef->body);
 }
 
-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;
+void ast_fdef_data_destroy_psv(ASTFDefData* fdef) {
+    free(fdef->name);
+    free(fdef->argv);
+    free(fdef);
 }
 
 ASTArgData* ast_arg_data_init(char* name) {
@@ -270,9 +214,12 @@ ASTArgData* ast_arg_data_init(char* name) {
 
 void ast_arg_data_destroy(ASTArgData* arg) { free(arg->name); }
 
-void ast_arg_print(ASTArgData* arg, int i) {
-    INDENT_BEGIN(i);
-    INDENT_TITLE("ASTArgData", arg);
-    INDENT_FIELD("name", "%s", arg->name);
-    INDENT_END;
+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

@@ -1,15 +1,15 @@
-#include "include/builtin.h"
-#include "include/ast.h"
-#include "include/exec.h"
-#include "include/util.h"
 #include <stdarg.h>
 #include <stdio.h>
 
-AST* builtin_sum(size_t argc, AST** argv) {
+#include "include/ast.h"
+#include "include/builtin.h"
+#include "include/exec.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]);
+        AST* arg = exec_exp(argv[i], parent);
         if (arg->type == AST_TYPE_EXC)
             return ast_init(
                 AST_TYPE_EXC,
@@ -27,9 +27,10 @@ AST* builtin_sum(size_t argc, AST** argv) {
     return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
 }
 
-AST* builtin_sub(size_t argc, AST** argv) {
-    log_dbg("Got here");
-    AST* first = exec_exp(*argv);
+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,
@@ -44,7 +45,7 @@ AST* builtin_sub(size_t argc, AST** argv) {
     ASTNumData total = *(ASTNumData*)first->data;
 
     for (int i = 1; i < argc; i++) {
-        AST* arg = exec_exp(argv[i]);
+        AST* arg = exec_exp(argv[i], parent);
         if (arg->type == AST_TYPE_EXC)
             return ast_init(
                 AST_TYPE_EXC,
@@ -62,9 +63,10 @@ AST* builtin_sub(size_t argc, AST** argv) {
     return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
 }
 
-AST* builtin_mul(size_t argc, AST** argv) {
-    log_dbg("Got here");
-    AST* first = exec_exp(*argv);
+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,
@@ -79,7 +81,7 @@ AST* builtin_mul(size_t argc, AST** argv) {
     ASTNumData total = *(ASTNumData*)first->data;
 
     for (int i = 1; i < argc; i++) {
-        AST* arg = exec_exp(argv[i]);
+        AST* arg = exec_exp(argv[i], parent);
         if (arg->type == AST_TYPE_EXC)
             return ast_init(
                 AST_TYPE_EXC,
@@ -97,9 +99,10 @@ AST* builtin_mul(size_t argc, AST** argv) {
     return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
 }
 
-AST* builtin_div(size_t argc, AST** argv) {
-    log_dbg("Got here");
-    AST* first = exec_exp(*argv);
+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,
@@ -114,7 +117,7 @@ AST* builtin_div(size_t argc, AST** argv) {
     ASTNumData total = *(ASTNumData*)first->data;
 
     for (int i = 1; i < argc; i++) {
-        AST* arg = exec_exp(argv[i]);
+        AST* arg = exec_exp(argv[i], parent);
         if (arg->type == AST_TYPE_EXC)
             return ast_init(
                 AST_TYPE_EXC,
@@ -131,3 +134,77 @@ AST* builtin_div(size_t argc, AST** argv) {
 
     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

@@ -1,9 +1,9 @@
+#include <stddef.h>
+#include <stdio.h> // IWYU pragma: keep. Req by util macros.
+
 #include "include/dlist.h"
 #include "include/util.h"
 
-#include <stddef.h>
-#include <stdio.h>
-
 DList* dlist_init(void) {
     DList* dlist = malloc(sizeof(DList));
 

src/exec.c

@@ -6,119 +6,100 @@
 #include "include/builtin.h"
 #include "include/exec.h"
 #include "include/htab.h"
-#include "include/stack.h"
+#include "include/scope.h"
 #include "include/util.h"
 
-extern AST* root;
-
-AST* exec_find(char* name);
-
 AST* exec_start(AST* ast) {
     log_dbg("Started execution.");
-    scope = stack_init();
 
-    HTab* global = htab_init();
+    if (!ast) return ast;
+
+    Scope* global = scope_init(NULL);
+    global->uses = 1;
 
     for (int i = 0; i < BUILTIN_FNS_LN; i++)
         htab_ins(
-            global, BUILTIN_FNS[i].name,
+            global->here, BUILTIN_FNS[i].name,
             ast_init(AST_TYPE_BIF, ast_bif_data_init(BUILTIN_FNS[i].fn))
         );
 
-    // Push global namespace to `scope`.
-    stack_push(scope, global);
+    log_dbg("Completed startup sequence.");
 
-    return exec_exp(ast);
+    AST* res = exec_exp(ast, global);
+
+    return res;
 }
 
-AST* exec_exp(AST* ast) {
+AST* exec_exp(AST* ast, Scope* parent) {
     switch (ast->type) {
-        case AST_TYPE_BLOCK: return exec_block(ast);
-        case AST_TYPE_CALL:  return exec_call(ast);
-        case AST_TYPE_NUM:   return ast;
-        case AST_TYPE_VREF:  return exec_vref(ast);
-        case AST_TYPE_VDEF:  return exec_vdef(ast);
-        case AST_TYPE_FDEF:  return exec_fdef(ast);
-        default:             printf("what\n"); exit(1);
+        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);
     }
 }
 
-AST* exec_block(AST* ast) {
+AST* exec_block(AST* ast, Scope* parent) {
     ASTBlockData* block = (ASTBlockData*)ast->data;
 
-    HTab* local = htab_init();
-    stack_push(scope, local);
+    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* last = exec_exp(block->inside[block->ln - 1]);
-
-    stack_pop(scope);
-    htab_destroy(local);
+    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) {
-    log_dbg("Started call execution.");
-    ASTCallData* data = (ASTCallData*)ast->data;
-    size_t argc = data->argc;
-    AST** argv = data->argv;
-    char* fname = data->to;
+AST* exec_call(AST* ast, Scope* parent) {
+    ASTCallData* calldata = (ASTCallData*)ast->data;
 
-    AST* fdef = exec_find(fname);
+    AST* exp = exec_exp(calldata->exp, parent);
 
-    if (fdef == NULL)
-        return ast_init(
-            AST_TYPE_EXC, ast_exc_data_init("No such function found.", NULL)
-        );
-
-    switch (fdef->type) {
+    switch (exp->type) {
         case AST_TYPE_BIF:
-            ASTBIFData bifdata = fdef->data;
-            return bifdata(argc, argv);
-        case AST_TYPE_FDEF: return exec_cf(fdef, argc, argv);
+            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("Good job!", NULL));
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("Uncallable.", NULL)
+            );
     }
 }
 
-AST* exec_cf(AST* ast, size_t argc, AST** argv) {
-    ASTFDefData* fdef = (ASTFDefData*)ast->data;
-    for (int i = 0; i < argc; i++) {
-        char* key = ((ASTArgData*)fdef->argv[i]->data)->name;
-        AST* val = argv[i];
-        htab_ins(scope->buf[scope->ln - 1], key, val);
-    }
+AST* exec_vdef(AST* ast, Scope* parent) {
+    // Use parent's scope.
+    exec_inherit_scope(ast, parent);
 
-    return exec_exp(fdef->body);
-}
-
-AST* exec_find(char* name) {
-    AST* val = NULL;
-
-    for (int i = scope->ln - 1; i >= 0; i--) {
-        HTab* lvl = scope->buf[i];
-        val = htab_get(lvl, name);
-        if (val != NULL) return val;
-    }
-
-    return NULL;
-}
-
-AST* exec_vdef(AST* ast) {
     ASTVDefData* data = (ASTVDefData*)ast->data;
-    AST* val = data->val;
+    AST* val = data->exp;
     char* key = data->name;
-    htab_ins(scope->buf[scope->ln - 1], key, val);
-    return exec_exp(val);
+    scope_add(parent, key, val); // Add variable definition to parent scope.
+    return exec_exp(val, parent);
 }
 
-AST* exec_vref(AST* ast) {
+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 = exec_find(vref->to);
+    AST* found = ast_find(parent, vref->to);
 
     if (found == NULL) {
         // TODO: Better memory management here.
@@ -130,15 +111,44 @@ AST* exec_vref(AST* ast) {
         return ast_init(AST_TYPE_EXC, ast_exc_data_init(msg, NULL));
     }
 
-    return exec_exp(found);
+    // return exec_exp(found, ast->scope);
+    return found;
 }
 
-AST* exec_fdef(AST* ast) {
+AST* exec_fdef(AST* ast, Scope* parent) {
+    ast->scope = scope_init(parent);
     ASTFDefData* fdef = (ASTFDefData*)ast->data;
-    AST* val = fdef->body;
+    AST* val = ast;
     char* key = fdef->name;
-    htab_ins(scope->buf[scope->ln - 1], key, val);
-    return val; // Function definitions return function body.
+    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/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/grammar.y

@@ -4,6 +4,7 @@
     #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*);
@@ -14,6 +15,7 @@
 %code requires {
     #include "../../src/include/ast.h"
     #include "../../src/include/dlist.h"
+    #include "../../src/include/builtin.h"
 }
 
 %union {
@@ -26,6 +28,12 @@
 
 %define parse.error verbose
 
+%token BOOLT // Boolean true (TRUE or T).
+%token BOOLF // Boolean false (FALSE or F).
+
+%token IF // if or ?.
+%token ELSE // else or :.
+
 %token BLOCKS // Block start {.
 %token BLOCKE // Block end }.
 
@@ -34,6 +42,7 @@
 %token SEP // Seperator ,.
 
 %token EQ // Equals =.
+%token DEQ // Double equals ==.
 
 %token EXPSEP // Expression seperator ;.
 
@@ -47,6 +56,8 @@
 
 %token NL // Newline.
 
+%token BACKSLASH
+
 %left ADD SUB
 %left MUL DIV
 %precedence NEG
@@ -85,6 +96,7 @@ inputend:
     %empty
     | input {
         root = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $1->buf, $1->ln));
+        dlist_destroypsv($1);
     }
     ;
 
@@ -121,28 +133,47 @@ block:
     ;
 
 exp:
+    // Number.
     NUM { $$ = ast_init(AST_TYPE_NUM, ast_num_data_init($1)); }
 
-    //| BLOCKS exp BLOCKE { $$ = $2; }
+    | BOOLT { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(1)); }
+    | BOOLF { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(0)); }
 
-    | BLOCKS block BLOCKE {
-        $$ = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $2->buf, $2->ln));
-    }
-
-    | SUB exp {
+    | exp DEQ exp {
         AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-1));
-        argv[1] = $2;
-        char* to = malloc(4);
-        strcpy(to, "mul");
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 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))
+        ));
     }
 
-    | GROUPS exp GROUPE { $$ = $2; }
+    | IF exp exp exp {
+        AST** argv = calloc(3, sizeof(AST*));
+        argv[0] = $2;
+        argv[1] = $3;
+        argv[2] = $4;
 
-    // Variable definition.
-    | WORD EQ exp {
-        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init($1, $3));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            3,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_if))
+        ));
+    }
+    | 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.
@@ -150,53 +181,140 @@ exp:
         $$ = 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($1, argc, argv));
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            ast_init(AST_TYPE_VREF, ast_vref_data_init($1))
+        ));
+    }
+
+    // Call (hacky convenient form).
+    | WORD GROUPS GROUPE {
+        size_t argc = 0;
+        AST** argv = NULL;
+        $$ = 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;
-        char* to = malloc(4);
-        strcpy(to, "sum");
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+        $$ = 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;
-        char* to = malloc(4);
-        strcpy(to, "sub");
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+        $$ = 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;
-        char* to = malloc(4);
-        strcpy(to, "mul");
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+        $$ = 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;
-        char* to = malloc(4);
-        strcpy(to, "div");
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
-    }
-
-    | WORD GROUPS arg GROUPE EQ exp {
-        size_t argc = $3->ln;
-        AST** argv = $3->buf;
-        argarr_destroypsv($3);
-        $$ = ast_init(AST_TYPE_FDEF, ast_fdef_data_init($1, argc, argv, $6));
+        $$ = 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

@@ -9,6 +9,8 @@
 HTab* htab_init() {
     HTab* htab = calloc(1, sizeof(HTab));
 
+    log_dbgf("HTAB %p", htab);
+
     return htab;
 }
 
@@ -29,7 +31,6 @@ void* htab_get(HTab* htab, char* key) {
 
 void htab_ins(HTab* htab, char* key, void* data) {
     size_t i = geti(key);
-    // assert((*htab)[i] == NULL);
     (*htab)[i] = data;
     log_dbgf("Inserted something to hash table @ index %lu", i);
 }

src/include/ast.h

@@ -1,50 +1,48 @@
 #ifndef AST_H
 #define AST_H
 
-#include "htab.h"
+#include "scope.h"
 #include <stdlib.h>
 
 // The type of an `AST`.
 typedef enum {
     // Primitive types.
-    AST_TYPE_NUM, // A number (float).
-    AST_TYPE_STR, // A string
-    AST_TYPE_INT, // An integer.
-    AST_TYPE_SYM, // A symbol.
-    AST_TYPE_EXC, // Exception.
+    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_ARG,   // A definition argument.
-    AST_TYPE_MAX = AST_TYPE_FDEF,
+    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; // The type of the `AST`.
     void* data;   // The data of the `AST`.
-    HTab* scope;  // The scope 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, HTab* scope);
-// Destroy an `AST`, recursively.
+AST* ast_init_scope(ASTType type, void* data, Scope* scope);
+// Destroy an `AST`.
 void ast_destroy(AST* ast);
-// 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);
 
 // A number.
 typedef double ASTNumData;
@@ -53,57 +51,81 @@ typedef double ASTNumData;
 ASTNumData* ast_num_data_init(double val);
 // Destroy an `ASTNumData`.
 void ast_num_data_destroy(ASTNumData* num);
-// Print an `ASTNumData`.
-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 {
-    char* msg;  // The exception message.
-    AST* trace; // The previous exception.
+    const char* msg; // The exception message.
+    AST* trace;      // The previous exception.
 } ASTExcData;
-// Create a new `ASTExecData.
-ASTExcData* ast_exc_data_init(char* msg, AST* trace);
+// 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);
-// Print an `ASTExecData`.
-void ast_exc_print(ASTExcData*, int i);
+
+// 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);
+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**));
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*));
+// Destroy an `ASTBIFData`.
+void ast_bif_data_destroy(ASTBIFData* bif);
 
-// There is no `ASTBIFData` destroy function, as function pointers are immortal.
-
-// A call (to a function).
+// 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;
 
 // Create a new `ASTCallData`.
-ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv);
+ASTCallData* ast_call_data_init(size_t argc, AST** argv, AST* exp);
 // Destroy an `ASTCallData`.
 void ast_call_data_destroy(ASTCallData* call);
-// Print an `ASTCallData`.
-void ast_call_print(ASTCallData*, int i);
 
-// A variable definition's data.
+// A variable definition. Associates a name with an expression.
 typedef struct {
     char* name;
-    AST* val;
+    AST* exp;
 } ASTVDefData;
 
 // Create a new `ASTVDefData`.
-ASTVDefData* ast_vdef_data_init(char* name, AST* val);
-// Destroys the `ASTVDefData`, `ASTVDefData->name`, and `ASTVDefData->val`.
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp);
+// Destroy an `ASTVDefData`.
 void ast_vdef_data_destroy(ASTVDefData* vdef);
-// Print an `ASTVDefData`.
-void ast_vdef_print(ASTVDefData*, int depth);
 
-// A variable reference's data.
+// A variable reference.
 typedef struct {
     char* to; // What the reference's to.
 } ASTVrefData;
@@ -112,8 +134,6 @@ typedef struct {
 ASTVrefData* ast_vref_data_init(char* to);
 // Destroy an `ASTVRefData`.
 void ast_vref_data_destroy(ASTVrefData* call);
-// Print an `ASTVRefData`.
-void ast_vref_print(ASTVrefData*, int i);
 
 // A code block.
 typedef struct {
@@ -125,22 +145,21 @@ typedef struct {
 ASTBlockData* ast_block_data_init(AST** inside, size_t ln);
 // Destroy an `ASTBlockData`, recursively.
 void ast_block_data_destroy(ASTBlockData* block);
-// Print an `ASTBlockData`.
-void ast_block_print(ASTBlockData*, int i);
+// Destroy an `ASTBlockData`.
+void ast_block_data_destroy_psv(ASTBlockData* block);
 
 typedef struct {
-    char* name;  // Function name.
-    size_t argc; // Argument count.
-    AST** argv;  // Argument vector.
-    AST* body;   // Function body.
+    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`.
+// Destroy an `ASTFDefData`, recursively.
 void ast_fdef_data_destroy(ASTFDefData* fdef);
-// Print an `ASTFDefData`.
-void ast_fdef_print(ASTFDefData* fdef, int i);
+// Destroy an `ASTFDefData`.
+void ast_fdef_data_destroy_psv(ASTFDefData* fdef);
 
 typedef struct {
     char* name; // Argument name.
@@ -150,7 +169,8 @@ typedef struct {
 ASTArgData* ast_arg_data_init(char* name);
 // Destroy an `ASTArgData`.
 void ast_arg_data_destroy(ASTArgData* arg);
-// Print an `ASTArgData`.
-void ast_arg_print(ASTArgData* arg, int i);
+
+// 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

@@ -2,22 +2,32 @@
 #define BUILTIN_H
 
 #include "ast.h"
+#include <stddef.h>
 
 // Sum some nums.
-AST* builtin_sum(size_t argc, AST** argv);
+AST* builtin_sum(size_t argc, AST** argv, Scope* parent);
 
 // Subtract nums.
-AST* builtin_sub(size_t argc, AST** argv);
+AST* builtin_sub(size_t argc, AST** argv, Scope* parent);
 
 // Multiply nums.
-AST* builtin_mul(size_t argc, AST** argv);
+AST* builtin_mul(size_t argc, AST** argv, Scope* parent);
 
 // Divide nums.
-AST* builtin_div(size_t argc, AST** argv);
+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);
+    AST* (*fn)(size_t argc, AST** argv, Scope* parent);
 };
 
 static struct builtin_data BUILTIN_FNS[] = {
@@ -25,6 +35,9 @@ static struct builtin_data BUILTIN_FNS[] = {
     { "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))
 

src/include/exec.h

@@ -2,28 +2,31 @@
 #define EXEC_H
 
 #include "ast.h"
-#include "stack.h"
-
-// The `Stack` of `HTab` that makes up the scope of any given `AST`.
-extern Stack* scope;
+#include "scope.h"
 
 // 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);
+AST* exec_exp(AST* ast, Scope* parent);
 // Execute the expressions of a block.
-AST* exec_block(AST* ast);
+AST* exec_block(AST* ast, Scope* parent);
 // Execute a call.
-AST* exec_call(AST* ast);
-// Execute a custom function call.
-AST* exec_cf(AST* ast, size_t argc, AST** argv);
-// Execute a variable reference.
-AST* exec_vref(AST* ast);
+AST* exec_call(AST* ast, Scope* parent);
 // Execute a variable definition.
-AST* exec_vdef(AST* ast);
+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);
+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/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/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/util.h

@@ -1,6 +1,8 @@
 #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.
 
@@ -10,6 +12,9 @@
 // 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.

src/lexer.c

@@ -3,6 +3,7 @@
 #include <limits.h>
 #include <math.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "include/dstr.h"
 #include "include/lexer.h"
@@ -26,7 +27,7 @@ void argarr_destroy(ArgArr* argarr) {
 void argarr_destroypsv(ArgArr* argarr) { free(argarr); }
 
 void argarr_add(ArgArr* argarr, AST* arg) {
-    if ((argarr->ln + 1) * argarr->sz > argarr->sz) {
+    if ((argarr->ln + 1) * sizeof(AST*) > argarr->sz) {
         argarr->sz *= 2;
         argarr->buf = realloc(argarr->buf, argarr->sz);
         log_dbgf(
@@ -72,7 +73,20 @@ double acc_float(int c) {
 
 char* acc_word(int c) {
     Dstr* val = dstr_init();
-    while (isalpha(*inp)) {
+    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++;
     }
@@ -98,8 +112,22 @@ int yylex() {
         return NUM;
     }
 
-    if (isalpha(c)) {
+    if (c == '=') {
+        yylval.strval = acc_deq(c);
+        if (!strcmp(yylval.strval, "=")) return EQ;
+        if (!strcmp(yylval.strval, "==")) return DEQ;
+    }
+
+    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;
     }
 
@@ -115,7 +143,10 @@ int yylex() {
         case ';':  return EXPSEP;
         case '{':  return BLOCKS;
         case '}':  return BLOCKE;
-        case '=':  return EQ;
+        // case '=':  return EQ;
+        case '\\': return BACKSLASH;
+        case '?':  return IF;
+        case ':':  return ELSE;
         default:   fprintf(stderr, "Unexpected character: %c\n", c);
     }
 

src/main.c

@@ -2,12 +2,11 @@
 #include <string.h>
 
 #include "include/ast.h"
+#include "include/ast_print.h"
 #include "include/dstr.h"
 #include "include/exec.h"
-#include "include/global.h"
-#include "include/htab.h"
+#include "include/gc.h"
 #include "include/lexer.h"
-#include "include/stack.h"
 #include "include/util.h"
 
 #include "../build/grammars/grammar.tab.h"
@@ -17,17 +16,16 @@ extern AST* root;
 extern char* inp;
 extern int yyparse();
 
-Stack* scope;
-
 int main(int argc, char** argv) {
 
     if (argc - 1 && strlen(argv[1]) > 0 && (inp = argv[1]) && !yyparse()) {
         log_dbg("Parsed successfully!\n");
-        ast_print(exec_start(root));
-        HTab* global = stack_pop(scope);
-        htab_destroy(global);
-        stack_destroy(scope);
-        ast_destroy(root);
+        ast_print(root);
+        AST* eval = exec_start(root);
+        ast_print(eval);
+        // ast_destroy(eval);
+        // ast_destroy(root);
+        gc_hack_free();
         exit(0);
     }
 
@@ -62,12 +60,16 @@ int main(int argc, char** argv) {
             ast_print(root);
 #endif
 
-            ast_print(exec_start(root));
-            HTab* global = stack_pop(scope);
-            htab_destroy(global);
-            stack_destroy(scope);
-
-            ast_destroy(root);
+            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);

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"

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 |