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commercialhaskell / rio

A standard library for Haskell
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What is the recommended way of list indexing? #202

Closed jeiea closed 4 years ago

jeiea commented 4 years ago

I searched something like (!!) :: [a] -> Int -> Maybe a but couldn't find one. So I leave this question.

snoyberg commented 4 years ago

The RIO.List module provides a few different list indexing functions which are total. RIO.List.Partial provides the partial (and not recommended) !! operator.

jeiea commented 4 years ago

Could not (!!) be total for compatibility? Then I have to define one myself or use partial (!!). Thanks for quick reply.

snoyberg commented 4 years ago

!! cannot be total. What would the result of [] !! 4 be?

jeiea commented 4 years ago

Nothing? I just wanted to receive Maybe type.

snoyberg commented 4 years ago

We try to match function and operator names and signatures from base, which is where the current setup comes from.

On Sat, Nov 16, 2019, 9:16 PM jeiea notifications@github.com wrote:

Nothing? I just wanted to receive Maybe type.

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