From fade9c496cebbc0caa97821cb85e9e56da31c57f Mon Sep 17 00:00:00 2001
From: Arnaud Bailly <arnaud@pankzsoft.com>
Date: Sat, 21 Mar 2026 09:06:47 +0100
Subject: Add more challenges and plans for enhancement of the interpreter

---
 lambda-calcul/haskell/src/Minilang/API.hs | 10 ++++++----
 lambda-calcul/haskell/src/Minilang/App.hs |  6 +++---
 2 files changed, 9 insertions(+), 7 deletions(-)

(limited to 'lambda-calcul/haskell/src')

diff --git a/lambda-calcul/haskell/src/Minilang/API.hs b/lambda-calcul/haskell/src/Minilang/API.hs
index 43baddf..0be70ff 100644
--- a/lambda-calcul/haskell/src/Minilang/API.hs
+++ b/lambda-calcul/haskell/src/Minilang/API.hs
@@ -131,13 +131,15 @@ newToken = first LBS.pack . uniformList 16
 
 data Challenge = Challenge
   { level :: Int,
-    expr :: Text
+    expr :: Text,
+    description :: Text,
+    answer :: Text
   }
   deriving (Eq, Show, Generic, ToJSON, FromJSON)
 
 defaultChallenges :: [Challenge]
 defaultChallenges =
-  [ Challenge 0 "x",
-    Challenge 1 "y",
-    Challenge 2 "(lam (x) x)"
+  [ Challenge 0 "x" "A lone free variable. What does x reduce to?" "x",
+    Challenge 1 "y" "Another free variable. What does y reduce to?" "y",
+    Challenge 2 "(lam (x) x)" "The identity function. What is its normal form?" "(lam (x) x)"
   ]
diff --git a/lambda-calcul/haskell/src/Minilang/App.hs b/lambda-calcul/haskell/src/Minilang/App.hs
index 915f264..cce48f7 100644
--- a/lambda-calcul/haskell/src/Minilang/App.hs
+++ b/lambda-calcul/haskell/src/Minilang/App.hs
@@ -151,11 +151,11 @@ postAnswer (Just token) expected = do
       result = evaluateOutputs outputs expected
   updateUserLastTest token result
   case result of
-    TestSucceeded -> do
+    TestSucceeded ->
       upgradeUserChallenge token
     TestFailed msg ->
       liftIO $ throwM $ err400 {errBody = "Test failed: " <> LBS.fromStrict (encodeUtf8 msg)}
-    TestErrored msg -> do
+    TestErrored msg ->
       liftIO $ throwM $ err500 {errBody = "Error evaluating answer: " <> LBS.fromStrict (encodeUtf8 msg)}
 
 data TestResult = TestSucceeded | TestFailed Text | TestErrored Text
@@ -167,7 +167,7 @@ isSuccess _ = False
 evaluateOutputs :: [Out] -> Text -> TestResult
 evaluateOutputs outputs expected =
   case outputs of
-    [Bye, Evaluated ast _ _] -> do
+    [Bye, Evaluated ast _ _] ->
       if pretty ast /= expected
         then TestFailed "Incorrect result"
         else TestSucceeded
-- 
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