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The main reason to learn category theory for Haskell is to learn how much of the Haskell meme complex is wrong. Otherwise, it won't help the typical newcomer. I

The main reason to learn category theory for Haskell is to learn how much of the Haskell meme complex is wrong. Otherwise, it won't help the typical newcomer. I think it's important to explain that Hask isn't a category, that Haskell's type system is unsound, that Haskell doesn't have sum types, etc. There are powerful applications of category theory to other parts of computer science. If one keeps in mind that Haskell is Just Another Programming Language, then one can apply category theory more generally and fully.

icrbow 5y ago
> Haskell doesn't have sum types Say what?..
- tome 5y ago
  I think it's because `Either a b` contains all of `undefined`, `Left undefined` and `Right undefined`. In other words, a technicality.
  - hutrdvnj 5y ago
    And this is not even the bottom of Haskell's unsoundness.
benrbray 5y ago
Agreed. Let me drop some references about the relationship between Haskell and Category Theory that really helped me untangle these concepts, in case it might help others. [1] Haskell/Category Theory https://en.wikibooks.org/wiki/Haskell/Category_theory#cite_note-1 https://en.wikibooks.org/wiki/Haskell/Category_theory#cite_n... [2] Bauer 2016, "Hask is Not a Category" http://math.andrej.com/2016/08/06/hask-is-not-a-category/ http://math.andrej.com/2016/08/06/hask-is-not-a-category/ [3] A reddit comment in response to #2, https://www.reddit.com/r/haskell/comments/4wk0gs/hask_is_not_a_category/d69j1de/ https://www.reddit.com/r/haskell/comments/4wk0gs/hask_is_not... [4] StackOverflow, "Is Hask even a Category?" https://stackoverflow.com/questions/48485660/is-hask-even-a-category/48490015#48490015 https://stackoverflow.com/questions/48485660/is-hask-even-a-...