From 48e795deccc678d650e79925221a308df71d7f75 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Thu, 17 May 2018 01:06:52 -0700
Subject: [PATCH] apply_substitution for PolyTypes

If I made an error it's likely here...
---
 schala-lang/src/typechecking.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/schala-lang/src/typechecking.rs b/schala-lang/src/typechecking.rs
index c9b31e5..f3cf6cf 100644
--- a/schala-lang/src/typechecking.rs
+++ b/schala-lang/src/typechecking.rs
@@ -102,7 +102,15 @@ impl PolyType {
   }
 
   fn apply_substitution(&self, s: &Substitution) -> PolyType {
-    unimplemented!()
+    let mut map: HashMap<Rc<String>, MonoType> = HashMap::new();
+    for (name, monotype) in s.0.iter() {
+      if let None = self.0.get(name) {
+        map.insert(name.clone(), monotype.clone());
+      }
+    }
+    let newsub = Substitution(map);
+    let new = self.1.apply_substitution(&newsub);
+    PolyType(self.0.clone(), new)
   }
 }