Re: Proposal: add replay function to Control.Monad.Cont.Class

Why not both? On Sun, Mar 7, 2021, 1:36 PM Zemyla wrote:

I kind of don't like it, because the continuation doesn't return anything but itself. I'd prefer something that works more like the setjmp function in C, taking a value and returning the value plus a function that lets it return the new value:

setJump :: MonadCont m => a -> m (a -> m b, a) setJump a = callCC $ \k -> let go b = k (go, b) in pure (go, a)

On Sun, Mar 7, 2021, 11:36 Carter Schonwald wrote:

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Yeah

On Sun, Mar 7, 2021 at 12:16 PM Edward Kmett wrote:

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I rather like label. +1 from me.

On Sun, Mar 7, 2021 at 1:25 AM Tom Ellis < tom-lists-haskell-cafe-2017@jaguarpaw.co.uk> wrote:

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On Sun, Mar 07, 2021 at 03:25:16AM +0000, Alexandre Esteves wrote:

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replay :: MonadCont m => m (m a) replay = callCC $ pure . fix

Using this in a do-notation block allows one to bind a name to the sub-block that starts immediately after. I reached for continuations to try to get this behavior for use with recursive flows without disrupting the reading of the main forward flow and found how to do it in https://jsdw.me/posts/haskell-cont-monad/ under the name "goto".

While "goto" is as familiar as a name can be, I feel "replay" more accurately conveys, that you can only 'go back', by stating what actually is happening - that a sub-block we're currently evaluating is replayed from its beginning.

Looks like a "label" more than a "goto" to me. Would "label" be a good name? _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

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