Add the define `def` procedure

2 files changed, 33 insertions, 0 deletions

diff --git a/src/bootstrap/main.c b/src/bootstrap/main.c
index 945e121..e8e530d 100755
--- a/src/bootstrap/main.c
+++ b/src/bootstrap/main.c
@@ -71,6 +71,7 @@ init(void) {
     MAKE_ENV_PROC(global_env, ">=", proc_num_greatereq_than);
     MAKE_ENV_PROC(global_env, "=", proc_num_equal);
     MAKE_ENV_PROC(global_env, "eq?", proc_equal);
+    MAKE_ENV_PROC(global_env, "def", proc_define);
 }
 
 void
diff --git a/src/bootstrap/primitives.c b/src/bootstrap/primitives.c
index 39229ff..af8e9da 100644
--- a/src/bootstrap/primitives.c
+++ b/src/bootstrap/primitives.c
@@ -601,6 +601,38 @@ proc_equal(Environment *env, Object *obj) {
     return obj_eq(a, b) ? obj_true : obj_false;
 }
 
+//
+// Variables and declarations.
+//
+
+Object *
+proc_define(Environment *env, Object *obj) {
+    if (obj == obj_nil || obj->cdr == obj_nil) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_NOT_ENOUGH_ARGS,
+        });
+        return obj_err;
+    }
+
+    Object *symbol = obj->car;
+    if (symbol->type != OBJ_TYPE_SYMBOL) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_WRONG_ARG_TYPE,
+        });
+        return obj_err;
+    }
+
+    Object *value = eval(env, obj->cdr->car);
+    if (value == obj_err) {
+        return obj_err;
+    }
+
+    // Make a copy of the symbol and to make them permanent in the environment.
+    env_update_symbol(env, obj_duplicate(symbol), obj_duplicate(value));
+    return obj_nil;
+}
 
 // TODO: fixnum left/right shift, mask, invert
 // TODO: add primitives for type transforms: string->symbol, symbol->string, etc