Some things are broken.

EVERYTHING IS BROKEN
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.

TODO.md

@@ -1,2 +1,5 @@
+FIX EXCEPTION PRINTING (probably broken because of string literals being dereferenced)
+
+
 1. Change editor to GNU Readline.
 2. Make variables persist through lines in the editor.

config.mk

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

src/ast.c

@@ -9,7 +9,7 @@ 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_BLOCK] = "BLOCK",        [AST_TYPE_EXC] = "EXCEPTION"
 };
 
 AST* ast_init(ASTType type, void* data) {
@@ -50,6 +50,7 @@ void ast_print_i(AST* ast, int i) {
             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;
@@ -77,8 +78,18 @@ void ast_num_print(ASTNumData* data, int i) {
     INDENT_END;
 }
 
-ASTExcData* ast_exc_data_init(char* msg) {
-    return (ASTExcData*) msg;
+ASTExcData* ast_exc_data_init(char* msg) { return (ASTExcData*)msg; }
+
+void ast_exc_print(ASTExcData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTExcData", data);
+    INDENT_FIELD("msg", "\"%s\"", *data);
+    INDENT_END;
+}
+
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**)) {
+    return (ASTBIFData*)fn;
 }
 
 ASTCallData* ast_call_data_init(char* to, size_t argc, AST** argv) {

src/builtin.c

@@ -0,0 +1,23 @@
+#include "include/builtin.h"
+#include "include/ast.h"
+#include "include/util.h"
+#include <stdarg.h>
+#include <stdio.h>
+
+AST* builtin_sum(size_t argc, AST** argv) {
+    log_dbg("Got here");
+    ASTNumData total = 0;
+
+    for (int i = 0; i < argc; i++) {
+        AST* arg = argv[i];
+        if (arg->type != AST_TYPE_NUM)
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("Sum can't sum some non-num arguments.")
+            );
+
+        total += *(ASTNumData*)arg->data;
+    }
+
+    return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
+}

src/exec.c

@@ -3,6 +3,7 @@
 #include <string.h>
 
 #include "include/ast.h"
+#include "include/builtin.h"
 #include "include/exec.h"
 #include "include/htab.h"
 #include "include/stack.h"
@@ -10,11 +11,17 @@
 
 extern AST* root;
 
+AST* exec_find(char* name);
+
 AST* exec_start(AST* ast) {
     scope = stack_init();
 
     HTab* global = htab_init();
 
+    htab_ins(
+        global, "sum", ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_sum))
+    );
+
     // Push global namespace to `scope`.
     stack_push(scope, global);
 
@@ -51,48 +58,20 @@ AST* exec_block(AST* ast) {
 
 AST* exec_call(AST* ast) {
     log_dbg("Started call execution.");
-    fflush(stdout);
-    ASTCallData* calldata = (ASTCallData*)ast->data;
-    if (calldata->argc >= 1) {
-        if (!strcmp(calldata->to, "sum")) {
-            AST* total = ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+    ASTCallData* data = (ASTCallData*)ast->data;
+    size_t argc = data->argc;
+    AST** argv = data->argv;
+    char* fname = data->to;
 
-            for (size_t i = 0; i < calldata->argc; i++) {
-                AST* arg = exec_exp(calldata->argv[i]);
+    AST* fdef = exec_find(fname);
 
-                if (arg->type != AST_TYPE_NUM) {
-                    return ast_init(
-                        AST_TYPE_EXC, ast_exc_data_init("Wrong type, fool.")
-                    );
-                }
-
-                *((ASTNumData*) total->data) += *((ASTNumData*)arg->data);
-            }
-
-            return total;
-        } /*else if (!strcmp(calldata->to, "sub")) {
-            double total = exec_exp(calldata->argv[0]);
-
-            for (size_t i = 1; i < calldata->argc;
-                 total -= exec_exp(calldata->argv[i++]));
-
-            return total;
-        } else if (!strcmp(calldata->to, "mul")) {
-            double total = exec_exp(calldata->argv[0]);
-
-            for (size_t i = 1; i < calldata->argc;
-                 total *= exec_exp(calldata->argv[i++]));
-
-            return total;
-        } else if (!strcmp(calldata->to, "div")) {
-            double total = exec_exp(calldata->argv[0]);
-
-            for (size_t i = 1; i < calldata->argc;
-                 total /= exec_exp(calldata->argv[i++]));
-
-            return total;
-            }*/
+    switch (fdef->type) {
+        case AST_TYPE_BIF:
+            ASTBIFData* bifdata = fdef->data;
+            return (*bifdata)(argc, argv);
+        default: return ast_init(AST_TYPE_EXC, ast_exc_data_init("Good job"));
     }
+
     return ast_init(AST_TYPE_EXC, ast_exc_data_init("No such function found."));
 }
 
@@ -105,8 +84,7 @@ AST* exec_find(char* name) {
         if (val != NULL) return val;
     }
 
-    log_dbgf("Could not find var %s", name);
-    exit(1);
+    return ast_init(AST_TYPE_EXC, ast_exc_data_init("Couln't find term."));
 }
 
 AST* exec_vdef(AST* ast) {

src/include/ast.h

@@ -16,6 +16,7 @@ typedef enum {
     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.
@@ -43,6 +44,15 @@ void ast_num_print(ASTNumData*, int i);
 typedef char* ASTExcData;
 ASTExcData* ast_exc_data_init(char* msg);
 void ast_exc_data_destroy(ASTExcData* exc);
+void ast_exc_print(ASTExcData*, int i);
+
+// A built-in function.
+typedef AST* (*ASTBIFData)(size_t argc, AST** argv);
+
+// Create a built-in function.
+ASTBIFData* ast_bif_data_init(AST* fn(size_t, AST**));
+
+// There is no `ASTBIFData` destroy function, as function pointers are immortal.
 
 typedef struct {
     char* to;    // What the call's to.

src/include/builtin.h

@@ -0,0 +1,12 @@
+#ifndef BUILTIN_H
+#define BUILTIN_H
+
+#include "ast.h"
+
+// Sum some nums.
+AST* builtin_sum(size_t argc, AST** argv);
+
+// The list of built-in functions.
+static AST* (*builtin_fns[])(size_t argc, AST** argv) = {builtin_sum};
+
+#endif