puffnfresh/roy

Monad syntax bug

raimohanska opened this issue · 3 comments

raimohanska commented

As in https://gist.github.com/4150252#comments

This works:

let main = do ioMonad
  _ <- putStrLn "a"
  putStrLn "b"

This does not:

let main = do ioMonad
  putStrLn "a"
  putStrLn "b"
raimohanska commented

So I made a fix, but I gotta admit I don't understand the compiler thorougly enough to be totally convinced it works under all circumstances. I added a new testcase (callbackmonad.roy) an existing test case to also include a line where there's just a side effect and no assignment.

joneshf commented

Hmm, There still seems to be a bug about this as of 0.2.2. It seems to still have to bind something in order for it to compile.

So something like:

let main = do someMonad
  someFunc 37

Gives this traceback:

/usr/lib/node_modules/roy/src/compile.js:152
    var result = n.accept({
                   ^
TypeError: Cannot call method 'accept' of undefined
    at compileNodeWithEnvToJsAST (/usr/lib/node_modules/roy/src/compile.js:152:20)
    at compileNode (/usr/lib/node_modules/roy/src/compile.js:150:16)
    at Object.n.accept.visitBind (/usr/lib/node_modules/roy/src/compile.js:317:27)
    at accept (/usr/lib/node_modules/roy/src/nodes.js:146:26)
    at compileNodeWithEnvToJsAST (/usr/lib/node_modules/roy/src/compile.js:152:20)
    at compileNode (/usr/lib/node_modules/roy/src/compile.js:150:16)
    at Object.n.accept.visitDo (/usr/lib/node_modules/roy/src/compile.js:388:27)
    at accept (/usr/lib/node_modules/roy/src/nodes.js:156:26)
    at compileNodeWithEnvToJsAST (/usr/lib/node_modules/roy/src/compile.js:152:20)
    at compileNode (/usr/lib/node_modules/roy/src/compile.js:150:16)