Re: [Haskell-beginners] Is there an idiom for this?

I think i saw a relevant stackoverflow question before, but I can't find it. Anyways, the answer said something like: liftA2 (&&) pred1 pred2 which has the type a -> Bool, as desired. The reader applicative gives your input to both predicates and (&&) is applied to their results. Hope I remembered this correctly. On Nov 16, 2015 4:01 AM, wrote:

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Today's Topics:

1. Is there an idiom for this? (Mark Carter) 2. Re: Is there an idiom for this? (emacstheviking)

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Message: 1 Date: Mon, 16 Nov 2015 11:44:35 +0000 From: Mark Carter To: beginners@haskell.org Subject: [Haskell-beginners] Is there an idiom for this? Message-ID: <5649C1A3.1010901@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Suppose I want to use an argument twice, as for example in the expression: (\x -> (pred1 x) and (pred2 x))

Is there a shorter way of doing this?

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Message: 2 Date: Mon, 16 Nov 2015 11:53:28 +0000 From: emacstheviking To: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell Subject: Re: [Haskell-beginners] Is there an idiom for this? Message-ID: Content-Type: text/plain; charset="utf-8"

I guess it depends on the final use cases... you could use currying to partially evaluate some stuff ready, locked and loaded as it were but the example you have given shows to distinct functions pres1 and pred2.

I guess the short answer is "yes" but it depends on how you do it!

:) Sean

On 16 November 2015 at 11:44, Mark Carter wrote:

...

Suppose I want to use an argument twice, as for example in the expression: (\x -> (pred1 x) and (pred2 x))

Is there a shorter way of doing this? _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners