[Haskell-cafe] Re: deleteBy type too restrictive

[Christian Maeder]

There's already a ticket for this proposal
http://hackage.haskell.org/trac/ghc/ticket/3399

Christian

Dan Rosén schrieb:
> Hello,
> 
> I realized today that the type for deleteBy in Data.List is too
> restrictive. The code is:
> 
> deleteBy                :: (a -> a -> Bool) -> a -> [a] -> [a]
> deleteBy _  _ []        = []
> deleteBy eq x (y:ys)    = if x `eq` y then ys else y : deleteBy eq x ys
> 
> though the type deleteBy :: (b -> a -> Bool) -> b -> [a] -> [a] will do
> good as well.
> 
> Is there a particular reason that the type has this restriction?
> Otherwise, where can I post a suggestion to have it untightened?
> 
> Best regards,
> Dan Rosén
> 
> references:
> http://haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/Data-List.html#v:deleteBy
> http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/src/Data-List.html#deleteBy
> 
> 
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