whats the purpose of Validation.sequence?

[tsechov]

hi guys,

could someone please explain the purpose of Validation.sequence (the static one)?

I need something that given a list of validations collects either the failures if there is any or the successes. I thought Validation.sequence was my friend but apparently its not...

thanks

[Runar Bjarnason]

Yeah, the implementation of `Validation.sequence` looks completely incorrect.

[tsechov]

if you can provide me with a specification I could file a pull request

[Tony Morris]

I agree. This is a bug in sequence.

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[Tony Morris]

Actually the one that is there should possibly stay, though perhaps renamed to indicate that it doesn't accumulate. A rename is ideal as it will ensure that existing clients break (won't compile), because it will accept a new argument (Semigroup).

I have written up a specification in Haskell.

https://gist.github.com/tonymorris/cbc051406b974df69e69

[tsechov]

thanks

Im gonna send a PR in the upcoming days
last question: what should the old one be renamed to? like sequenceNoncumulate?

[Rúnar Bjarnason]

Honestly, the old one looks broken. It seems like it would never return anything in the case of any failures in the list.

[Mark Perry]

I created two issues, one to fix and rename the existing method and the other to implement sequence with a semigroup.

See:

https://github.com/functionaljava/functionaljava/issues/162

https://github.com/functionaljava/functionaljava/issues/163

I look forward to your PR Tsechov covering both issues.

Regards,

Mark