Move syntax to separate module

Makefile

@@ -10,6 +10,7 @@ OBJS = \
 	src/lexer.c.o    \
 	src/object.c.o   \
 	src/parser.c.o   \
+	src/syntax.c.o   \
 	src/tokens.c.o
 
 MAIN_OBJS = $(OBJS) src/main.c.o

src/eval.c

@@ -3,6 +3,7 @@
 #include "builtins.h"
 #include "lexer.h"
 #include "parser.h"
+#include "syntax.h"
 
 #include <assert.h>
 #include <stddef.h>
@@ -53,31 +54,8 @@ struct Object *eval(struct Object *const object)
     struct Object *const args = object->pair.b;
 
     if (Object_is_symbol(func_expr)) {
-        if (strcmp(func_expr->s, "quote") == 0) {
-            assert(Object_is_pair(args));
-            assert(args->pair.b == NULL);
-            return args->pair.a;
-        }
-
-        if (strcmp(func_expr->s, "if") == 0) {
-            assert(Object_is_pair(args));
-            struct Object *const cond = args->pair.a;
-            struct Object *const then_else_list = args->pair.b;
-            assert(then_else_list);
-            assert(Object_is_pair(then_else_list));
-            struct Object *const then_branch = then_else_list->pair.a;
-            struct Object *const else_list = then_else_list->pair.b;
-            assert(else_list);
-            assert(Object_is_pair(else_list));
-            struct Object *const else_branch = else_list->pair.a;
-            assert(else_list->pair.b == NULL);
-
-            if (Object_is_false(cond)) {
-                return eval(else_branch);
-            } else {
-                return eval(then_branch);
-            }
-        }
+        if (strcmp(func_expr->s, "quote") == 0) return syntax_quote(args);
+        if (strcmp(func_expr->s, "if")    == 0) return syntax_if(args);
     }
 
     struct Object *const func = eval(func_expr);

src/syntax.c

@@ -0,0 +1,34 @@
+#include "syntax.h"
+
+#include "eval.h"
+#include "object.h"
+
+#include <assert.h>
+
+struct Object *syntax_if(struct Object *const args)
+{
+    assert(Object_is_pair(args));
+    struct Object *const cond = args->pair.a;
+    struct Object *const then_else_list = args->pair.b;
+    assert(then_else_list);
+    assert(Object_is_pair(then_else_list));
+    struct Object *const then_branch = then_else_list->pair.a;
+    struct Object *const else_list = then_else_list->pair.b;
+    assert(else_list);
+    assert(Object_is_pair(else_list));
+    struct Object *const else_branch = else_list->pair.a;
+    assert(else_list->pair.b == NULL);
+
+    if (Object_is_false(cond)) {
+        return eval(else_branch);
+    } else {
+        return eval(then_branch);
+    }
+}
+
+struct Object *syntax_quote(struct Object *const args)
+{
+    assert(Object_is_pair(args));
+    assert(OBJECT_IS_NULL(args->pair.b));
+    return args->pair.a;
+}

src/syntax.h

@@ -0,0 +1,9 @@
+#ifndef __ARCANE_SCHEME_LISP_SYNTAX_H__
+#define __ARCANE_SCHEME_LISP_SYNTAX_H__
+
+#include "object.h"
+
+struct Object *syntax_if(struct Object *args);
+struct Object *syntax_quote(struct Object *args);
+
+#endif