[Haskell-beginners] Re: \x -> x < 0.5 && x > -0.5

[Heinrich Apfelmus]

Michael Mossey wrote:
> Is there a nifty way to write
> 
> filter (\x -> x < 0.5 && x > -0.5) xs
> 
> without explicitly using x?
> 
> Maybe arrows? I have a vague understanding that arrows can "send" an
> argument to more than one computation.

That's a job for the reader monad.


Lambda Fu, form 53 - silent reader of truth

    import Control.Monad
    import Control.Monad.Reader

    filter (liftM2 (&&) (< 0.5) (> -0.5)) xs



Regards,
apfelmus

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