Updated README.md.

NOTE: changed versioning system slightly.

README.md

@@ -1,20 +1,20 @@
 # SCL: Simple CAS Language
 
-Version v1.0-beta
+*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
+its current state, SCL can be used as a functional programming language capable
-of operations and local variables. The codebase is about 1,400 lines of C,
+of performing simple arithmetic. The codebase is about 2,000 lines of
-including a parser, interpreter, and runtime. It uses a linked environment
+handwritten C, including a parser, interpreter, and runtime. It uses a linked
-scoping model.
+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
-```
+> (\(x) 2 * x)(5)
-
+= 10
-You can also define your own functions and variables:
+> f(g) g(2)
-
+> f(\(x) 2 * x)
-```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
 = 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
+> factorial(n) {
-> diff(f, x:sym, 2)
+>   if (n == 0) { 1 }
-= 12x^2
+>   else { n * factorial(n - 1) }
+> }
 ```
 
-SCL will dynamically decide on types, but you can state them explicitly as
+SCL's syntax is quite flexible. The above function could be more concisely
-well:
+written as:
 
 ```scl
-> f(x: int): int = 2x
+> factorial(n) ? n == 0 1 n * factorial(n - 1)
-> 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.
 ```

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
+  - [x] Exec variable use
-  - [ ] Exec variable definition
+  - [x] Exec variable definition
-  - [ ] Exec function 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.
+EXCEPTION HANDLING: exception ast type should have as data a giant enum of
-1. Differenciate parameters and arguments -- params for function definitions,
+possible types, rather than a char* message. A description of each type could be
-arguments for function calls
+handled under the exception type and print logic. For now, executor checks
-2. Add scope field to all ASTs, and new scope layer for those that need it.
+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.

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
+apply(f, x) f(x)
-
+apply(\(x) x + 1, 2)
-f(5)

src/ast.c

@@ -2,24 +2,12 @@
 #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] = "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 = gc_alloc(sizeof(AST), GC_TYPE_AST);
 
@@ -52,35 +40,16 @@ void ast_destroy(AST* ast) {
 
     switch (ast->type) {
         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(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;
-        default:
-            log_dbgf("Unknown ast type %d (max: %d)", ast->type, AST_TYPE_MAX);
-    }
-
-    // If there're no more `AST`s linked to the scope, free.
-    if (ast->scope && !--ast->scope->uses) scope_destroy_psv(ast->scope);
-
-    free(ast);
-}
-
-void ast_destroy_psv(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_psv(ast->data); break;
-        case AST_TYPE_VREF:  ast_vref_data_destroy(ast->data); break;
-        case AST_TYPE_VDEF:  ast_vdef_data_destroy_psv(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);
     }
@@ -88,35 +57,6 @@ void ast_destroy_psv(AST* ast) {
     free(ast);
 }
 
-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("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) {
     talloc(ASTNumData, num);
 
@@ -127,14 +67,16 @@ ASTNumData* ast_num_data_init(double val) {
 
 void ast_num_data_destroy(ASTNumData* num) { free(num); }
 
-void ast_num_print(ASTNumData* data, int i) {
+ASTBoolData* ast_bool_data_init(int val) {
-    INDENT_BEGIN(i);
+    talloc(ASTBoolData, bol);
 
-    INDENT_FIELD("data", "%lf", *data);
+    *bol = val;
 
-    INDENT_END;
+    return bol;
 }
 
+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;
@@ -147,33 +89,35 @@ void ast_exc_data_destroy(ASTExcData* exc) {
     free(exc);
 }
 
-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;
-}
-
 ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*)) {
     return (ASTBIFData*)fn;
 }
 
 void ast_bif_data_destroy(ASTBIFData* bif) { return; }
 
-ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv) {
+// 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->exp = exp;
-
-    call->to = to;
     call->argc = argc;
     call->argv = argv;
 
@@ -182,63 +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_data_destroy_psv(ASTCallData* call) {
+// VDef.
-    if (!call) return;
-    free(call->to);
-    call->to = NULL;
-    free(call->argv);
-    call->argv = NULL;
-    free(call);
-}
 
-void ast_call_print(ASTCallData* data, int i) {
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp) {
-    INDENT_BEGIN(i);
-
-    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) {
     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_data_destroy_psv(ASTVDefData* vdef) {
+// VRef.
-    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;
-}
 
 ASTVrefData* ast_vref_data_init(char* to) {
     talloc(ASTVrefData, vref);
@@ -253,15 +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));
 
@@ -283,16 +182,6 @@ void ast_block_data_destroy_psv(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;
-}
-
 ASTFDefData*
 ast_fdef_data_init(char* name, size_t argc, AST** argv, AST* body) {
     ASTFDefData* fdef = malloc(sizeof(ASTFDefData));
@@ -317,18 +206,6 @@ void ast_fdef_data_destroy_psv(ASTFDefData* fdef) {
     free(fdef);
 }
 
-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;
-}
-
 ASTArgData* ast_arg_data_init(char* name) {
     ASTArgData* arg = malloc(sizeof(ASTArgData));
     arg->name = name;
@@ -337,13 +214,6 @@ 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);

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

@@ -1,10 +1,10 @@
-#include "include/builtin.h"
-#include "include/ast.h"
-#include "include/exec.h"
-#include "include/util.h"
 #include <stdarg.h>
 #include <stdio.h>
 
+#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;
 
@@ -28,7 +28,8 @@ AST* builtin_sum(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_sub(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    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(
@@ -63,7 +64,8 @@ AST* builtin_sub(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_mul(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    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(
@@ -98,7 +100,8 @@ AST* builtin_mul(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_div(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    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(
@@ -131,3 +134,77 @@ AST* builtin_div(size_t argc, AST** argv, Scope* parent) {
 
     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

@@ -4,7 +4,6 @@
 
 #include "include/ast.h"
 #include "include/builtin.h"
-#include "include/dlist.h"
 #include "include/exec.h"
 #include "include/htab.h"
 #include "include/scope.h"
@@ -39,9 +38,15 @@ AST* exec_exp(AST* ast, Scope* parent) {
             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);
     }
 }
@@ -60,49 +65,29 @@ AST* exec_block(AST* ast, Scope* parent) {
 }
 
 AST* exec_call(AST* ast, Scope* parent) {
-    log_dbg("Started call execution.");
+    ASTCallData* calldata = (ASTCallData*)ast->data;
-    ASTCallData* data = (ASTCallData*)ast->data;
-    size_t argc = data->argc;
-    AST** argv = data->argv;
-    char* fname = data->to;
 
-    ast->scope = parent;
+    AST* exp = exec_exp(calldata->exp, parent);
 
-    AST* fdef = ast_find(ast->scope, fname);
+    switch (exp->type) {
-
-    if (fdef == NULL)
-        return ast_init(
-            AST_TYPE_EXC, ast_exc_data_init("No such function found.", NULL)
-        );
-
-    switch (fdef->type) {
         case AST_TYPE_BIF:
-            ASTBIFData bifdata = fdef->data;
+            ASTBIFData bifdata = exp->data;
-            return bifdata(argc, argv, parent);
+            return bifdata(calldata->argc, calldata->argv, parent);
-        case AST_TYPE_FDEF: return exec_cf(fdef, argc, argv);
+        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) {
-    Scope* callscope = scope_init(ast->scope);
-    ASTFDefData* fdef = (ASTFDefData*)ast->data;
-    for (int i = 0; i < argc; i++) {
-        char* key = ((ASTArgData*)fdef->argv[i]->data)->name;
-        AST* val = argv[i];
-        scope_add(callscope, key, val);
-    }
-
-    return exec_exp(fdef->body, callscope);
-}
-
 AST* exec_vdef(AST* ast, Scope* parent) {
     // Use parent's scope.
     exec_inherit_scope(ast, parent);
 
     ASTVDefData* data = (ASTVDefData*)ast->data;
-    AST* val = data->val;
+    AST* val = data->exp;
     char* key = data->name;
     scope_add(parent, key, val); // Add variable definition to parent scope.
     return exec_exp(val, parent);
@@ -126,20 +111,31 @@ AST* exec_vref(AST* ast, Scope* parent) {
         return ast_init(AST_TYPE_EXC, ast_exc_data_init(msg, NULL));
     }
 
-    return exec_exp(found, ast->scope);
+    // 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;
-    log_dbgf("IS THIS SUSPICIOUS??? %i", fdef->body->type);
     AST* val = ast;
     char* key = fdef->name;
     scope_add(parent, key, val);
-    // TODO: Create lambda functions.
     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) {

src/gc.c

@@ -48,7 +48,7 @@ void gc_hack_free() {
                         ((AST*)gc->p)->type, AST_TYPE_MAX, gc, gc->p
                     );
                 }
-                ast_destroy_psv(gc->p);
+                ast_destroy(gc->p);
                 break;
             case GC_TYPE_SCOPE: scope_destroy_psv(gc->p); break;
         }

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
@@ -122,34 +133,47 @@ block:
     ;
 
 exp:
+    // Number.
     NUM { $$ = ast_init(AST_TYPE_NUM, ast_num_data_init($1)); }
 
-    // Function definitions.
+    | BOOLT { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(1)); }
-    | WORD GROUPS arg GROUPE EQ exp {
+    | BOOLF { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(0)); }
-        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));
-    }
 
-    | BLOCKS block BLOCKE {
+    | exp DEQ exp {
-        $$ = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $2->buf, $2->ln));
-    }
-
-    | SUB exp {
         AST** argv = calloc(2, sizeof(AST*));
-        argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(-1));
+        argv[0] = $1;
-        argv[1] = $2;
+        argv[1] = $3;
-        char* to = malloc(4);
+
-        strcpy(to, "mul");
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+            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.
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
-    | WORD EQ exp {
+            3,
-        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init($1, $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.
@@ -157,46 +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);
+        $$ = ast_init(AST_TYPE_CALL,
-        strcpy(to, "sum");
+            ast_call_data_init(
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+                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);
+        $$ = ast_init(AST_TYPE_CALL,
-        strcpy(to, "sub");
+            ast_call_data_init(
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+                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);
+        $$ = ast_init(AST_TYPE_CALL,
-        strcpy(to, "mul");
+            ast_call_data_init(
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+                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);
+        $$ = ast_init(AST_TYPE_CALL,
-        strcpy(to, "div");
+            ast_call_data_init(
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(to, 2, argv));
+                2,
+                argv,
+                ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_div))
+            )
+        );
     }
 %%

src/include/ast.h

@@ -10,6 +10,7 @@ typedef enum {
     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.
 
@@ -24,6 +25,7 @@ typedef enum {
     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;
@@ -39,14 +41,8 @@ typedef struct {
 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`, recursively.
-void ast_destroy(AST* ast);
 // Destroy an `AST`.
-void ast_destroy_psv(AST* 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;
@@ -55,8 +51,14 @@ 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 {
@@ -67,8 +69,20 @@ typedef struct ASTEXCDATA {
 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, Scope* scope);
@@ -78,38 +92,40 @@ ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**, Scope*));
 // Destroy an `ASTBIFData`.
 void ast_bif_data_destroy(ASTBIFData* bif);
 
-// A call (to a function).
+// A lambda.
 typedef struct {
-    char* to;    // What the call's to.
+    PARS;      // The parameters the lambda can accept.
-    size_t argc; // Argument count.
+    AST* body; // The body expression to be executed.
-    AST** argv;  // Argument vector.
+} 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` recursively.
-void ast_call_data_destroy(ASTCallData* call);
 // Destroy an `ASTCallData`.
-void ast_call_data_destroy_psv(ASTCallData *call);
+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);
+ASTVDefData* ast_vdef_data_init(char* name, AST* exp);
-// Destroys the `ASTVDefData`, `ASTVDefData->name`, and `ASTVDefData->val`.
-void ast_vdef_data_destroy(ASTVDefData* vdef);
 // Destroy an `ASTVDefData`.
-void ast_vdef_data_destroy_psv(ASTVDefData* vdef);
+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;
@@ -118,8 +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 {
@@ -133,13 +147,10 @@ ASTBlockData* ast_block_data_init(AST** inside, size_t ln);
 void ast_block_data_destroy(ASTBlockData* block);
 // Destroy an `ASTBlockData`.
 void ast_block_data_destroy_psv(ASTBlockData* block);
-// Print an `ASTBlockData`.
-void ast_block_print(ASTBlockData*, int i);
 
 typedef struct {
     char* name; // Function name.
-    size_t argc; // Argument count.
+    ARGS;       // Function args.
-    AST** argv;  // Argument vector.
     AST* body;  // Function body.
 } ASTFDefData;
 
@@ -149,8 +160,6 @@ ASTFDefData* ast_fdef_data_init(char* name, size_t argc, AST** argv, AST* body);
 void ast_fdef_data_destroy(ASTFDefData* fdef);
 // Destroy an `ASTFDefData`.
 void ast_fdef_data_destroy_psv(ASTFDefData* fdef);
-// Print an `ASTFDefData`.
-void ast_fdef_print(ASTFDefData* fdef, int i);
 
 typedef struct {
     char* name; // Argument name.
@@ -160,10 +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 a name in the scope.
+// 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

@@ -2,6 +2,7 @@
 #define BUILTIN_H
 
 #include "ast.h"
+#include <stddef.h>
 
 // Sum some nums.
 AST* builtin_sum(size_t argc, AST** argv, Scope* parent);
@@ -15,6 +16,15 @@ 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);
@@ -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

@@ -12,14 +12,14 @@ AST* exec_exp(AST* ast, Scope* parent);
 AST* exec_block(AST* ast, Scope* parent);
 // Execute a call.
 AST* exec_call(AST* ast, Scope* parent);
-// Execute a custom function call.
-AST* exec_cf(AST* ast, size_t argc, AST** argv);
 // 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);
 

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"
@@ -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

@@ -2,6 +2,7 @@
 #include <string.h>
 
 #include "include/ast.h"
+#include "include/ast_print.h"
 #include "include/dstr.h"
 #include "include/exec.h"
 #include "include/gc.h"
@@ -61,6 +62,13 @@ int main(int argc, char** argv) {
 
             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();
         }
 

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 |