Fix dot documentation

[treeowl]

I goofed up and made the strat1 `dot` strat1 = strat1 law too strong. Fix that. Also, add laws for strat `dot` rseq and strat `dot` rpar.

[Borgvall]

You are contradicting yourself. In the commit line 308 you say: "strat dot rseq == strat" for all strat, but if strat = r0 it is not.

Diese Nachricht wurde von meinem Android Mobiltelefon mit GMX Mail gesendet.Am 09.06.18, 18:16, David Feuer [email protected] schrieb: @treeowl commented on this pull request.

In Control/Parallel/Strategies.hs:

-- --- > strat2 dot strat1 == strat2 . withStrategy strat1 +-- 'r0', 'rseq', and 'rpar' are all one-sided identities of 'dot': +-- +-- > strat dot r0 == strat +-- > strat dot rseq == strat +-- > strat dot rpar == strat

r0 dot rseq is not r0. But rseq dot r0 = r0.

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[treeowl]

I mistyped that comment. It's corrected on the web.

On Sat, Jun 9, 2018, 3:50 PM Johannes Röhl [email protected] wrote:

You are contradicting yourself. In the commit line 308 you say: "strat dot rseq == strat" for all strat, but if strat = r0 it is not.

Diese Nachricht wurde von meinem Android Mobiltelefon mit GMX Mail gesendet.Am 09.06.18, 18:16, David Feuer [email protected] schrieb: @treeowl commented on this pull request.

In Control/Parallel/Strategies.hs:

-- --- > strat2 dot strat1 == strat2 . withStrategy strat1 +-- 'r0', 'rseq', and 'rpar' are all one-sided identities of 'dot': +-- +-- > strat dot r0 == strat +-- > strat dot rseq == strat +-- > strat dot rpar == strat

r0 dot rseq is not r0. But rseq dot r0 = r0.

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[Borgvall]

In the edited version of your comment you sai: "r0 dot rseq is not r0", but in line 308 you say:

-- strat `dot` rseq == strat [for all strat even r0]

So you are still contradicting yourself.

[treeowl]

Yes, I did make a mistake. r0 `dot` rseq is indeed r0 after all.

[Kleidukos]

@treeowl can I let you merge it?

[treeowl]

@treeowl can I let you merge it?

I don't understand the question. I don't have permission to merge things to master.

[Borgvall]

As this old merge request has been resurrected, I revisited it. My current point of view is, that the documentation is as weird as the implementation of dot, and the documentation changes of @treeowl simply expose this fact.

IMHO the dotcombinator should be deprecated. The reasonable way to "compose two strategies sequentially" is to use Control.Monad.>=>.

[konsumlamm]

I agree that r0 `dot` rseq == `r0 is counterintuitive. >=>/<=< indeed gives you a more intuitive (IMO) strategy composition, e.g. r0 <=< rseq == rseq.

We should definitely fix the documentation (although there's still an unresolved review), but I'm sympathetic to deprecating dot, unless someone has an argument why this strategy composition makes sense.