GHCi is being too "helpful"

Philip Weaver philip.weaver at
Fri Jan 25 10:57:17 EST 2008

You want -fno-print-bind-results, which can be passed to ghci at the command
line or set within ghci using :set.

I found your answer in this guide:

- Phil

On Jan 25, 2008 7:37 AM, Dinko Tenev <dinko.tenev at> wrote:

> Hi everyone,
> When evaluating an IO monad in GHCi from the 6.6.1 distribution, the
> REPL tries to be a bit too smart about printing out the returned
> value.  For example, () values are not printed:
>    Prelude System.Directory> setCurrentDirectory "work"
>    Prelude System.Directory>
> ...but String, or, as far as I can see, any other values, do get printed:
>    Prelude System.Directory> getCurrentDirectory
>    "/home/shinobi"
>    Prelude System.Directory> set
> In my particular case, the value printed is a 250,000-element list --
> waiting for the value to print out is not an option.  I don't want to
> see the whole list at once, but do need to examine parts of it,
> subject it to intermediate transformations, etc.
> Is there any way to suppress this output and revert to the old
> behavior, where the value was simply bound to "it", without being
> printed?
> Thanks,
> D. Tenev
> _______________________________________________
> Glasgow-haskell-users mailing list
> Glasgow-haskell-users at
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