From 7fe9c669d256bafcd6fdf31df1a1fc14004db4e1 Mon Sep 17 00:00:00 2001
From: Eric Holk <eholk@cs.indiana.edu>
Date: Tue, 28 Apr 2015 16:19:19 -0400
Subject: [PATCH] Better linting of ifs

---
 harlan/front/lint.scm | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/harlan/front/lint.scm b/harlan/front/lint.scm
index 11e641e..c86a217 100644
--- a/harlan/front/lint.scm
+++ b/harlan/front/lint.scm
@@ -47,10 +47,17 @@
              dups)))))
   
   (define (check-if expr env context)
-    (if (eq? context 'expr)
-        (match expr
-          ((if ,t ,c)
-           (err expr "One-armed if found in expression context. Try adding a case for if the test is false.")))))
+    (match expr
+      ((if ,t ,c)
+       (if (eq? context 'expr)
+           (err expr "One-armed if found in expression context. Try adding a case for if the test is false.")
+           (begin (check-expr t env)
+                  (check-expr c env))))
+      ((if ,t ,c ,a)
+       (check-expr t env)
+       (check-expr c env)
+       (check-expr a env))
+      (,else (err expr "Incorrect number of arguments for if. If should consist of a test, a then expression/statement and also an else expression/statement."))))
 
   (define (check-error expr env context)
     (match expr