PureScriptでREPLを作る

こんなかんじや

code:purs(hs)

module Main where

import Prelude

import Effect (Effect)

import Effect.Aff (Aff, launchAff_)

import Effect.Class (liftEffect)

import Effect.Console (log)

import Readline (readLine)

main :: Effect Unit

main = do

launchAff_ loop

loop :: Aff Unit

loop = do

line <- readLine "user> "

case line of

":q" -> pure unit

":Q" -> pure unit

_ -> do

liftEffect $ log line

loop

read :: String -> String

read s = s

eval :: String -> String

eval s = s

print :: String -> String

print s = s

rep :: String -> String

rep = read >>> eval >>> print

code:purs(hs)

module Readline where

import Prelude

import Data.Either (Either(..))

import Effect (Effect)

import Effect.Aff (Aff, Canceler, effectCanceler, makeAff)

import Effect.Exception (Error)

import Node.ReadLine (close, createConsoleInterface, noCompletion, prompt, setLineHandler, setPrompt)

readLine :: String -> Aff String

readLine pm = makeAff handler

where

handler :: (Either Error String -> Effect Unit) -> Effect Canceler

handler next = do

interface <- createConsoleInterface noCompletion

setPrompt pm interface

prompt interface

interface

# setLineHandler \str -> do

close interface

next $ Right str

pure $ effectCanceler $ close interface

参考