simple repl

.gitignore

@@ -1 +1 @@
-bin/
+dist/

bc.cabal

@@ -6,7 +6,6 @@ license:             MIT
 license-file:        LICENSE
 author:              Veit Heller
 maintainer:          veit@veitheller.de
-copyright:           
 category:            Language
 build-type:          Simple
 extra-source-files:  ChangeLog.md, README.md
@@ -14,7 +13,7 @@ cabal-version:       >=1.10
 
 executable bc
   main-is:             Main.hs
-  other-modules:       
+  hs-source-dirs:      src/
-  build-depends:       base >=4.9 && <4.10
+  build-depends:       base >=4.9 && <4.10, haskeline, unix
   hs-source-dirs:      src
   default-language:    Haskell2010

src/BC/Config.hs

@@ -1,5 +1,7 @@
-module Bc.Prompt where
+module BC.Config where
 
 versionStr = "0.1.0.0"
 
-prompt = "> "
+promptStr = "> "
+
+returnStr = "=> "

src/BC/Prompt.hs

@@ -1,24 +1,45 @@
 module BC.Prompt (startPrompt) where
 
+import System.Console.Haskeline
+import System.Posix.Signals
+
 import BC.Config
 
 printHeader :: IO ()
 printHeader = do
-  putStrLn "bc (better calculator) version " ++ versionStr
+  putStrLn $ "bc (better calculator) version " ++ versionStr
   putStrLn "Copyright 2017 Veit Heller"
   putStrLn "This is free software with ABSOLUTELY NO WARRANTY.\n"
 
 
+output :: [Char] -> InputT IO ()
+output out = outputStrLn $ returnStr ++ out
+
+
 prompt :: IO ()
-prompt = runInputT settings $ poll prompt
+prompt = runInputT defaultSettings $ poll promptStr
   where poll p = do
-        input <- getInputLine p
+          input <- getInputLine p
-        case input of
+          case input of
-          Nothing -> return ""
+            Nothing -> do
-          Just str -> return str
+              output "Bye!"
+              return ()
+            Just "quit" -> do
+              output "Bye!"
+              return ()
+            Just str -> do
+              output str
+              poll p
+
+
+installHandlers :: IO ()
+installHandlers = do
+  installHandler keyboardSignal (Catch (putStrLn "\n(interrupt) type quit to exit")) Nothing
+  return ()
 
 
 startPrompt :: IO ()
 startPrompt = do
   printHeader
+  installHandlers
   prompt