From 1d1f0efc7de1eaa0c8a6b503892c2f950008fde6 Mon Sep 17 00:00:00 2001
From: Arnaud Bailly <arnaud@pankzsoft.com>
Date: Tue, 28 Oct 2025 20:14:16 +0100
Subject: wip: port REPL from minilang

---
 lambda-calcul/haskell/src/Minilang/REPL/IO.hs | 36 +++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 lambda-calcul/haskell/src/Minilang/REPL/IO.hs

(limited to 'lambda-calcul/haskell/src/Minilang/REPL/IO.hs')

diff --git a/lambda-calcul/haskell/src/Minilang/REPL/IO.hs b/lambda-calcul/haskell/src/Minilang/REPL/IO.hs
new file mode 100644
index 0000000..90b1e5d
--- /dev/null
+++ b/lambda-calcul/haskell/src/Minilang/REPL/IO.hs
@@ -0,0 +1,36 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE ViewPatterns #-}
+
+module Minilang.REPL.IO where
+
+import Control.Monad.Catch
+import Control.Monad.Reader
+import Control.Monad.State
+import Data.Text (unpack, pack)
+import Data.Text.IO as Text
+import Minilang.REPL.Types
+import System.IO (Handle, hFlush)
+import System.IO.Error (isEOFError)
+
+data IOEnv = IOEnv
+  { inputHandle :: Handle,
+    outputHandle :: Handle,
+    repl :: REPLEnv
+  }
+
+newtype CONSOLE m a = CONSOLE {runConsole :: StateT IOEnv m a}
+  deriving (Functor, Applicative, Monad, MonadTrans, MonadState IOEnv)
+
+instance MonadREPL (CONSOLE IO) where
+  input = get >>= lift . (\h -> (interpret <$> hGetLine h) `catch` \(isEOFError -> True) -> pure EOF) . inputHandle
+  output a = get >>= lift . flip hPutStrLn (pack $ show a) . outputHandle
+  prompt = get >>= lift . (\h -> hPutStr h "λΠ> " >> hFlush h) . outputHandle
+  getEnv = get >>= pure . repl
+  setEnv e' = modify $ \e -> e {repl = e'}
+  load = lift . try . Text.readFile . unpack
+
+instance (MonadThrow m) => MonadThrow (CONSOLE m) where
+  throwM = lift . throwM
+
+instance (MonadCatch m) => MonadCatch (CONSOLE m) where
+  CONSOLE m `catch` f = CONSOLE $ m `catch` \e -> runConsole (f e)
-- 
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