Re: [Haskell-cafe] Re: Is StateT what I need?

Am Montag, 17. Dezember 2007 21:06 schrieb ChrisK:

Andre Nathan wrote:

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Hello (Newbie question ahead :

I tried this for insertProc, but it obviously doesn't work... what would be the correct way to do this?

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insertProc :: Pid -> StateT PsMap IO PsInfo insertProc pid = do proc <- procInfo pid -- XXX this is obviously wrong... psMap <- get put (Map.insert pid proc psMap) return (proc)

I see that using "lift" makes it compile (Control.Monad.Trans.lift):

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insertProc pid = do proc <- lift (procInfo pid)

By the way, be careful with identifiers named “proc”. There is a syntax extension (arrow notation) which introduces a new keyword “proc”. Best wishes, Wolfgang