From a47f72f510b7195f96779715d1dfac7cdda8e295 Mon Sep 17 00:00:00 2001
From: Brandon Rozek <rozekbrandon@gmail.com>
Date: Sat, 9 Jun 2018 10:16:03 -0400
Subject: [PATCH] Added builtin cons operation

---
 lval/expressions.c | 15 +++++++++++++++
 lval/expressions.h |  1 +
 lval/operations.c  |  1 -
 prompt.c           |  1 +
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/lval/expressions.c b/lval/expressions.c
index 77fc9e3..0400984 100644
--- a/lval/expressions.c
+++ b/lval/expressions.c
@@ -165,3 +165,18 @@ lval* builtin_len(lval* a) {
 	lval_del(a);
 	return x;
 }
+
+lval* builtin_cons(lval* a) {
+	LASSERT(a, a->cell[0]->type != LVAL_QEXPR, "Function 'cons' passed incorrect type on first argument")
+	LASSERT(a, a->cell[1]->type == LVAL_QEXPR, "Function 'cons' passed incorrect type on second argument")
+	LASSERT(a, a->count == 2, "Function 'cons' passed an incorrect number of arguments")
+	
+	lval* x = lval_qexpr();
+	x = lval_add(x, lval_pop(a, 0));
+	x = lval_join(x, lval_pop(a, 0));
+
+	lval_del(a);
+
+	return x;
+
+}
diff --git a/lval/expressions.h b/lval/expressions.h
index 5893a01..8cc2a59 100644
--- a/lval/expressions.h
+++ b/lval/expressions.h
@@ -41,5 +41,6 @@ lval* builtin_eval(lval* a);
 lval* lval_join(lval* x, lval* y);
 lval* builtin_join(lval* a);
 lval* builtin_len(lval* a);
+lval* builtin_cons(lval* a);
 
 #endif
diff --git a/lval/operations.c b/lval/operations.c
index e011b34..67611ad 100644
--- a/lval/operations.c
+++ b/lval/operations.c
@@ -50,7 +50,6 @@ lval* lval_eval(lval* v) {
 	return v;
 }
 
-
 void lval_del(lval* v) {
 	switch (v->type) {
 		case LVAL_LONG: break;
diff --git a/prompt.c b/prompt.c
index eb08752..3701c44 100644
--- a/prompt.c
+++ b/prompt.c
@@ -170,6 +170,7 @@ lval* builtin(lval* a, char* func) {
 	if (strcmp("eval", func) == 0) { return builtin_eval(a); }
 	if (strcmp("len", func) == 0) { return builtin_len(a); }
 	if (strcmp("init", func) == 0) { return builtin_init(a); }
+	if (strcmp("cons", func) == 0) { return builtin_cons(a); }
 	if (strstr("+-/*^%", func)) { return builtin_op(a, func); }
 	if (strcmp("min", func) == 0) { return builtin_op(a, func); }
 	if (strcmp("max", func) == 0) { return builtin_op(a, func); }