[Haskell-cafe] Getting types inside a function in ghci

[Christopher Done]

On 29 October 2013 22:36, martin <martin.drautzburg at web.de> wrote:

> is there a way to determine types of symbols which are not toplevel but
> inside a function?
>

Not at present without transformation. There are two reasonably reliable
approaches:

Insert noisy holes/make intentional type errors:
http://ghc.haskell.org/trac/ghc/wiki/Holes#Insertingdeliberatetypeerrors

Implicit parameters:
http://ghc.haskell.org/trac/ghc/wiki/Holes#Implicitparameters

Holes will land in GHC to support this explicitly. I don't know what
version of GHC has/will have this.

Alternatively, you can use ghc-mod (https://github.com/kazu-yamamoto/ghc-mod)
which, if you can get it to work, can tell you the types of sub-expressions.

Lastly, the next version of the FP Complete IDE gives you types of
sub-expressions just by clicking on them or selecting them out of the box.
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