From c3a175e808b279eb415bcb5dbcb9db5f34035f98 Mon Sep 17 00:00:00 2001
From: Arnaud Bailly <arnaud@pankzsoft.com>
Date: Fri, 17 Oct 2025 09:52:06 +0200
Subject: feat: add basic application to evaluate "programs"

The main simply reads from its stdin, evaluates its input, and dump
the result of the evaluation.
---
 lambda-calcul/haskell/src/Minilang/IO.hs          | 32 ++++++-----------------
 lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs |  2 +-
 2 files changed, 9 insertions(+), 25 deletions(-)

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

diff --git a/lambda-calcul/haskell/src/Minilang/IO.hs b/lambda-calcul/haskell/src/Minilang/IO.hs
index bfcb125..c468316 100644
--- a/lambda-calcul/haskell/src/Minilang/IO.hs
+++ b/lambda-calcul/haskell/src/Minilang/IO.hs
@@ -1,40 +1,24 @@
-{-# LANGUAGE DuplicateRecordFields #-}
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE NamedFieldPuns #-}
-{-# LANGUAGE RecordWildCards #-}
-{-# LANGUAGE TypeSynonymInstances #-}
-{-# OPTIONS_GHC "-fno-warn-orphans" #-}
-
 module Minilang.IO where
 
 import qualified Data.ByteString as BS
+import qualified Data.Text as Text
 import Data.Text.Encoding
   ( decodeUtf8With,
     encodeUtf8,
   )
 import Data.Text.Encoding.Error (lenientDecode)
-import Minilang.Lambda.Eval hiding (rho)
-import Minilang.Parser
-import Minilang.Type
-import Prettyprinter
-import Prettyprinter.Render.Text
+import Minilang.Lambda.Eval (eval)
 import System.IO (Handle)
 
--- | Read an `AST` from @hin@ handle, evaluate it and dump the result
+-- | Read a "program" from @hin@ handle, evaluate it and dump the result
 -- on @hout@.
 runEval :: Handle -> Handle -> IO ()
 runEval hin hout = do
-  programText <- decodeUtf8With lenientDecode <$> BS.hGetContents hin
-  let ast = parseProgram False programText
-      ρ = EmptyEnv
-      γ = EmptyContext
-  (ρ', _) <- loadProgram ast ρ γ
-  let val = eval ast ρ'
+  programText <- Text.unpack . decodeUtf8With lenientDecode <$> BS.hGetContents hin
+  let ast = read programText
+      env = mempty
+      result = eval ast env
 
   BS.hPut
     hout
-    ( encodeUtf8
-        ( renderStrict $ layoutPretty defaultLayoutOptions $ pretty val
-        )
-        <> "\n"
-    )
+    (encodeUtf8 (Text.pack (show result) <> "\n"))
diff --git a/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs b/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
index 68b01be..0829186 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
@@ -6,7 +6,7 @@ data Term
   = Var Text
   | Lam Text Term
   | App Term Term
-  deriving (Show, Eq)
+  deriving (Show, Read, Eq)
 
 type Env = [(Text, Term)]
 
-- 
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