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

[ChrisK]

Andre Nathan wrote:
> Hello (Newbie question ahead :
>
> I tried this for insertProc, but it obviously doesn't work... what would
> be the correct way to do this?
> 
>> 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):

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