wip: port REPL from minilang

1 files changed, 11 insertions, 0 deletions

diff --git a/lambda-calcul/haskell/src/Minilang/Lambda/Unify.hs b/lambda-calcul/haskell/src/Minilang/Lambda/Unify.hs
index ad06552..df66113 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda/Unify.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda/Unify.hs
@@ -1,4 +1,5 @@
 --  ported from https://www.cs.cornell.edu/courses/cs3110/2011sp/Lectures/lec26-type-inference/type-inference.htm
+{-# LANGUAGE LambdaCase #-}
 module Minilang.Lambda.Unify where
 
 import Data.Text (Text)
@@ -12,6 +13,16 @@ data Type
 
 infixr 5 :->
 
+pretty :: Type -> Text
+pretty = \case
+  TyVar x -> x
+  f :-> g ->
+    let left = case f of
+          TyVar _ -> pretty f
+          _ -> "(" <> pretty f <> ")"
+        right = pretty g
+     in left <> " -> " <> right
+
 -- invariant: no identifier on the left hand-side can appear in
 -- an earlier term in the list, ie. the list is in "dependency order"
 -- and forms a DAG.