From 6fcdb655a6581963a873224ad01f92b4e88f0de3 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Sun, 17 Oct 2021 16:08:58 +0200
Subject: Cleanup if call in eval function

---
 src/bootstrap/primitives.c | 84 ++++++++++++++++++----------------------------
 1 file changed, 33 insertions(+), 51 deletions(-)

(limited to 'src/bootstrap/primitives.c')

diff --git a/src/bootstrap/primitives.c b/src/bootstrap/primitives.c
index 0403e3a..ab147d4 100644
--- a/src/bootstrap/primitives.c
+++ b/src/bootstrap/primitives.c
@@ -1,6 +1,5 @@
 #define DEBUG_OBJ(MSG,OBJ) printf((MSG)); display(OBJ); printf("\n");
-
-Object * proc_if(Environment *env, Object *obj);
+static Object *proc_if;
 
 Object *
 eval(Environment *env, Object *root) {
@@ -41,32 +40,34 @@ eval_start:
                     });
                     return obj_err;
                 }
-                if (val->type == OBJ_TYPE_PROCEDURE) {
-                    // TODO: This is very messy, needs refactoring.
-                    if (val->proc == proc_if) {
-                        Object *obj = root->cdr;
-                        if (obj == obj_nil || obj->cdr == obj_nil) {
-                            error_push((Error){
-                                .type = ERR_TYPE_RUNTIME,
-                                .value = ERR_NOT_ENOUGH_ARGS,
-                            });
-                            return obj_err;
-                        }
-                        Object *car = obj->car;
-                        Object *cdr = obj->cdr;
-                        Object *condition = eval(env, car);
-                        if (condition == obj_err) {
-                            return obj_err;
-                        }
-                        if (condition == obj_true) {
-                            root = cdr->car;
-                        } else if (cdr->cdr != obj_nil) {
-                            root = cdr->cdr->car;
-                        } else {
-                            return obj_nil;
-                        }
-                        goto eval_start;
+
+                // Primitive `if` procedure with TCO.
+                if (val == proc_if) {
+                    Object *obj = root->cdr;
+                    if (obj == obj_nil || obj->cdr == obj_nil) {
+                        error_push((Error){
+                            .type = ERR_TYPE_RUNTIME,
+                            .value = ERR_NOT_ENOUGH_ARGS,
+                        });
+                        return obj_err;
                     }
+                    Object *car = obj->car;
+                    Object *cdr = obj->cdr;
+                    Object *condition = eval(env, car);
+                    if (condition == obj_err) {
+                        return obj_err;
+                    }
+                    if (condition == obj_true) {
+                        root = cdr->car;
+                    } else if (cdr->cdr != obj_nil) {
+                        root = cdr->cdr->car;
+                    } else {
+                        return obj_nil;
+                    }
+                    goto eval_start;
+                }
+
+                if (val->type == OBJ_TYPE_PROCEDURE) {
                     ret = val->proc(env, root->cdr);
                     goto eval_success;
                 }
@@ -138,6 +139,11 @@ eval_lambda:
                 root = root->car;
                 goto eval_start;
             }
+            error_push((Error){
+                .type = ERR_TYPE_RUNTIME,
+                .value = ERR_OBJ_NOT_CALLABLE,
+            });
+            return obj_err;
         } break;
     }
 
@@ -482,30 +488,6 @@ proc_or(Environment *env, Object *obj) {
     return obj_false;
 }
 
-Object *
-proc_if(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 *car = obj->car;
-    Object *cdr = obj->cdr;
-    Object *condition = eval(env, car);
-    if (condition == obj_err) {
-        return obj_err;
-    }
-    if (condition == obj_true) {
-        return eval(env, cdr->car);
-    }
-    if (cdr->cdr != obj_nil) {
-        return eval(env, cdr->cdr->car);
-    }
-    return obj_nil;
-}
-
 Object *
 proc_cond(Environment *env, Object *obj) {
     if (obj == obj_nil) {
-- 
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