Am Freitag, 5. Dezember 2008 19:03 schrieb Александър Л. Димитров:

Hey list,

I'm currently using :set -Wall in my .ghci to enforce some good coding practices on my side. Something like missing type signatures and the like. It has saved me quite a lot of hassle over the last couple of days as I experimented more with Haskell. But it seems, -Wall may be just a little too… overzealous:

Prelude> 2^2

Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from a use of `^' at <interactive>:1:0-2

Warning: Defaulting the following constraint(s) to type `Integer' `Integral t' arising from a use of `^' at <interactive>:1:0-2

Warning: Defaulting the following constraint(s) to type `Integer' `Num t' arising from a use of `^' at <interactive>:1:0-2

Warning: Defaulting the following constraint(s) to type `Integer' `Integral t' arising from a use of `^' at <interactive>:1:0-2 4

(I've shortened ghci's response a bit)

So, do you have a good (recommended) set of -W switches for a newbie playing around in GHCi, so I can learn a good style? Forgive me if it's somewhere on page one of some book or tutorials - I've read so many of both, I'm beginning to forget things.

Turn off those warnings you don't want, like $ ghci -Wall -fno-warn-type-defaults GHCi, version 6.8.3: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. Prelude> 2^2 4 A list of warning options is in section 5.7 of the user's guide (unless it's moved in the 6.10 branch).

Thanks, Aleks

Cheers, Daniel