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List:       haskell-beginners
Subject:    Re: [Haskell-beginners] \x -> x < 0.5 && x > -0.5
From:       Darrin Thompson <darrinth () gmail ! com>
Date:       2009-10-23 15:25:57
Message-ID: a2e649c70910230825t3fa93c0clb735bc4193a61bf () mail ! gmail ! com
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On Fri, Oct 23, 2009 at 10:25 AM, pl <pl.listas@gmail.com> wrote:
>
>    filter ((<=0.5) . abs) xs
>

pure (&&) <*> (< 0.5) <*> (> -0.5)

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

Someone suggested that this was an example of the reader monad but I
don't get that.

> :i (->)
data (->) a b   -- Defined in GHC.Prim
instance Monad ((->) r) -- Defined in Control.Monad.Instances
instance Functor ((->) r) -- Defined in Control.Monad.Instances
instance Applicative ((->) a) -- Defined in Control.Applicative

That's what I see working here.

--
Darrin
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