Breakage with ghc-6.10

John Goerzen jgoerzen at
Fri Oct 10 14:29:08 EDT 2008

Duncan Coutts wrote:
> Ok, lets look at hslogger:
> src/System/Log/Logger.hs:333:20:
>     Couldn't match expected type `Maybe Logger'
>            against inferred type `IO Logger'
>     In a stmt of a 'do' expression: result <- Map.lookup lname newlt
> Ah ok, so that's the change in Map.lookup to return Maybe rather than in
> any monad. So that's an easy source code fix:
> result <- maybe (fail "Arrgh!") return (Map.lookup lname newlt)

There are actually more instances than this in the code, but I already
have fixed it in my git tree.  I guess it's time to make a release.

-- John

> Note of course this will also work with the previous implementation of
> lookup.
> Duncan

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