hs-duktape

Haskell bindings for duktape, a very compact embedded ECMAScript (JavaScript) engine.

Usage

Here's a simple REPL example:

module Main where

import Scripting.Duktape
import Control.Monad (forever)
import Data.ByteString.Char8 (pack)
import System.IO (hFlush, stdout)

main :: IO ()
main = do
  dukm <- createDuktapeCtx
  case dukm of
    Nothing -> putStrLn "I can't even (start Duktape)"
    Just duk -> forever $ do
      putStr "duktape> "
      hFlush stdout
      retVal <- evalDuktape duk =<< return . pack =<< getLine
      case retVal of
        Left e -> putStrLn $ "Duktape error: " ++ e
        Right Nothing -> putStrLn "No result"
        Right (Just v) -> print v

Aeson's Value type is used for exchanging values between Haskell and ECMAScript.
lens-aeson is a good library for working with Value, um, values.

You can also call functions that are on the global object (or any object that's on the global object):

dukm <- createDuktapeCtx
bresult <- callDuktape (fromJust dukm) Nothing "boolTest" [Bool True, Bool True, Bool False] -- boolTest(true, true, false)
aresult <- callDuktape (fromJust dukm) (Just "NumFuns") "sum" [Number 1, Number 2] -- NumFuns.sum(1, 2)

And expose Haskell functions (same as with calls: set on global or a property of global):

dukm <- createDuktapeCtx
let dbl (Number x) = return $ Number $ x * 2 ∷ IO Value
    dbl _ = return $ String "wtf"
reD ← exposeFnDuktape (fromJust ctx) Nothing "double" dbl 

The functions must be of type IO (), IO Value, Value -> IO Value, Value -> Value -> IO Value... and so on, up to 5 arguments. If you need more, use an Object Value, seriously.

Development

Use stack to build.

$ stack build

$ stack test && rm tests.tix

Contributing

Please feel free to submit pull requests! Bugfixes and simple non-breaking improvements will be accepted without any questions :-)

By participating in this project you agree to follow the Contributor Code of Conduct.

The list of contributors is available on GitHub.

License

Licensed under the MIT license (see to the LICENSE file).
Haskell bindings: Copyright (c) 2015 Greg V greg@unrelenting.technology
Duktape: Copyright (c) 2013-2015 by Duktape authors (see duktape/AUTHORS.rst)