1 files changed, 24 insertions, 2 deletions
diff --git a/lambda-calcul/haskell/test/Minilang/Lambda/EvalSpec.hs b/lambda-calcul/haskell/test/Minilang/Lambda/EvalSpec.hs
index d772fe0..f07b5a2 100644
--- a/lambda-calcul/haskell/test/Minilang/Lambda/EvalSpec.hs
+++ b/lambda-calcul/haskell/test/Minilang/Lambda/EvalSpec.hs
@@ -2,8 +2,11 @@ module Minilang.Lambda.EvalSpec (spec) where
 
 import Control.Concurrent (threadDelay)
 import Control.Concurrent.Async (race_)
-import Minilang.Lambda.Eval (Term (..), Value, eval, normalise)
-import Test.Hspec (Spec, describe, it, pending, shouldBe)
+import Minilang.Lambda.Eval (Term (..), Value (..), eval, normalise)
+import Test.Hspec (Spec, describe, it, shouldBe)
+import Test.Hspec.QuickCheck (prop)
+import Data.Text (pack)
+import Test.QuickCheck (NonEmptyList (..), arbitrary, forAll, (===))
 
 spec :: Spec
 spec = do
@@ -65,6 +68,25 @@ spec = do
       normalise (App (App add' one) one)
         `shouldBe` two
 
+  describe "integer literals" $ do
+    -- An integer literal is already a normal form: normalise must return it unchanged.
+    prop "any integer literal normalises to itself" $ \n ->
+      normalise (Num n) === Num (n :: Int)
+
+    -- eval on a bare Num must always produce the VNum value form, never a closure
+    -- or neutral, regardless of the integer's sign or magnitude.
+    prop "eval of any integer literal produces VNum" $ \n ->
+      eval [] (Num n) === VNum (n :: Int)
+
+    -- A number is not a function.  Applying it to any argument must leave a stuck
+    -- neutral application: App (Num n) (normalise arg).  We test this with free
+    -- variables as arguments, which are themselves already in normal form.
+    prop "an integer in function position produces a stuck application" $
+      forAll arbitrary $ \n ->
+        forAll (getNonEmpty <$> arbitrary) $ \x ->
+          normalise (App (Num n) (Var (pack x)))
+            === App (Num (n :: Int)) (Var (pack x))
+
   -- describe "call-by-name eval" $ do
   --   it "evaluates 'x' as itself" $ do
   --     normalise' (Var "x") `shouldBe` Var "x"