From 9e0f8b8a14ba04830b40733eae0f1848ba9ab8d2 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Thu, 17 May 2018 02:29:17 -0700
Subject: [PATCH] InferError

---
 schala-lang/src/typechecking.rs | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/schala-lang/src/typechecking.rs b/schala-lang/src/typechecking.rs
index 5252499..ec2f459 100644
--- a/schala-lang/src/typechecking.rs
+++ b/schala-lang/src/typechecking.rs
@@ -238,9 +238,11 @@ impl TypeContext {
   pub fn type_check_ast(&mut self, ast: &parsing::AST) -> TypeResult<String> {
     let ref block = ast.0;
     let mut infer = Infer::new();
-    let output = infer.infer_block(block)?;
-
-	Ok(format!("{:?}", output))
+    let output = infer.infer_block(block);
+    match output {
+      Ok(s) => Ok(format!("{:?}", s)),
+      Err(s) => Err(format!("Error: {:?}", s))
+    }
   }
 }
 
@@ -250,12 +252,19 @@ struct Infer {
 
 }
 
+#[derive(Debug)]
+enum InferError {
+  CannotUnify(MonoType, MonoType),
+  OccursCheckFailed(Rc<String>, MonoType),
+  UnknownIdentifier(Rc<String>)
+}
+
 impl Infer {
   fn new() -> Infer {
     Infer { }
   }
 
-  fn infer_block(&mut self, block: &Vec<parsing::Statement>) -> TypeResult<MonoType> {
+  fn infer_block(&mut self, block: &Vec<parsing::Statement>) -> Result<MonoType, InferError> {
     Ok(MonoType::Const(TypeConst::Unit))
   }
 }