From 821bc6250b041fa6919c7c7f9703be652aa3bd2f Mon Sep 17 00:00:00 2001
From: tmeissner <programming@goodcleanfun.de>
Date: Fri, 10 May 2019 00:36:28 +0200
Subject: [PATCH] Add lookup of builtins

---
 chapter_10/lispy.c | 23 ++++++++++++++++++++++-
 chapter_10/lispy.h |  1 +
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/chapter_10/lispy.c b/chapter_10/lispy.c
index bafa75d..6405bb2 100644
--- a/chapter_10/lispy.c
+++ b/chapter_10/lispy.c
@@ -289,7 +289,7 @@ lval* lval_eval_sexpr(lval* v) {
     }
 
     /* Call builtin with operator */
-    lval* result = builtin_op(v, f->sym);
+    lval* result = builtin(v, f->sym);
     lval_del(f);
     return result;
 
@@ -338,6 +338,27 @@ lval* lval_take(lval* v, size_t i) {
 }
 
 
+lval* builtin(lval* a, char* func) {
+
+    /* Check for builtin functions */
+    if (strcmp("list", func) == 0) {return builtin_list(a);}
+    if (strcmp("head", func) == 0) {return builtin_head(a);}
+    if (strcmp("tail", func) == 0) {return builtin_tail(a);}
+    if (strcmp("join", func) == 0) {return builtin_join(a);}
+    if (strcmp("eval", func) == 0) {return builtin_eval(a);}
+
+    /* Check for operators */
+    if (strstr("+-*/%^", func) ||
+        strcmp("min", func) == 0 || strcmp("max", func) == 0) {
+        return builtin_op(a, func);
+    }
+
+    lval_del(a);
+    return lval_err("Unknown function!");
+
+}
+
+
 lval* builtin_op(lval* a, char* op) {
 
     /* Ensure all arguments are numbers */
diff --git a/chapter_10/lispy.h b/chapter_10/lispy.h
index 3074aba..1d9f3df 100644
--- a/chapter_10/lispy.h
+++ b/chapter_10/lispy.h
@@ -70,6 +70,7 @@ void lval_println(lval* v);
 /* language built-in operators and functions */
 long min(long x, long y);
 long max(long x, long y);
+lval* builtin(lval* a, char* func);
 lval* builtin_op(lval* a, char* op);
 lval* builtin_head(lval* a);
 lval* builtin_tail(lval* a);