#ghci

[jwilsondev]

GHCI Tip: Get the names of all functions in a module

Have a module and want to know what functions it exposes without opening up the source? Or what if you don't have the source but want to know what you can do with it?

Simple:

ghci> :load AModule.hs [1 of 1] Compiling Just.AModule ( AModule.hs, interpreted ) Ok, modules loaded: Just.AModule. ghci> -- notice the name of the module loaded ghci> :browse Just.AModule data Cat a = Cat a getName :: Cat a -> a newName :: a -> Cat a

Yes this module is dumb. The key here is the :browse command. Perhaps "overview" or "summary" would have been better names, but I think browse is fairly descriptive.

[sevennet-blog]

How to: Why does ghci desugar type lists and type families? Can this be selectively disabled?

How to: Why does ghci desugar type lists and type families? Can this be selectively disabled?

Why does ghci desugar type lists and type families? Can this be selectively disabled?

I’m trying to make the types ghci displays for my libraries as intuitive as possible, but I’m running into a lot of difficulties when using more advanced type features.

Let’s say I have this code in a file:

{-# LANGUAGE TypeFamilies #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeOperators #-} import…

View On WordPress

[kuznero]

Using GHCi in a sandbox

# mkdir _temp # cabal sandbox init # cabal install cmdargs # ghci -no-user-package-db -package-db .cabal-sandbox/i386-linux-ghc-7.6.1-packages.conf.d # Prelude> import System.Console.CmdArgs # Prelude System.Console.CmdArgs> ???