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ZipList is Bind #219

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worldmaker18349276 opened this issue Aug 2, 2024 · 1 comment

worldmaker18349276 commented Aug 2, 2024

purescript-lists/src/Data/List/ZipList.purs

Lines 57 to 66 in b113451

    
           instance zipListIsNotBind 
        
             :: Fail (Text """ 
        
               ZipList is not Bind. Any implementation would break the associativity law. 
        
               Possible alternatives: 
        
                   Data.List.List 
        
                   Data.List.Lazy.List 
        
               """) 
        
             => Bind ZipList where 
        
               bind = unsafeCrashWith "bind: unreachable"

ZipList is Bind, in which join is just diagonal. It's also Monad and MonadPlus.

Example: https://try.purescript.org/?gist=4888527a78d71d12df75fa628acd4719

Author

worldmaker18349276 commented Aug 5, 2024 •

edited

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by the way,

fix-sized array is Bind: https://github.com/sigma-andex/purescript-fast-vect/blob/209c35d9b616370dc2bb7efaa4c1d2ac4fd394bf/src/Data/FastVect/FastVect.purs#L75

ZipArray (finite nonempty array using zip longest strategy) is Bind: https://gist.github.com/ajnsit/b2aebc5f70d1192122bde7bf5f18592a#file-ziparray-purs-L100

Map is Bind: https://github.com/purescript/purescript-ordered-collections/blob/b9c8ec72b53ee56d6cb6dc962d5ad7ea4708b438/src/Data/Map/Internal.purs#L164

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