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0 pointspjmlp11y ago0 comments

You need it due to type inference, otherwise the engine cannot infer all the types properly.

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sampo11y ago· 2 in thread

I don't think this is true. Because: Standard ML does not have let rec, but can do type inference just fine.

pjmlpOP11y ago

https://realworldocaml.org/v1/en/html/variables-and-function...

"OCaml distinguishes between nonrecursive definitions (using let) and recursive definitions (using let rec) largely for technical reasons: the type-inference algorithm needs to know when a set of function definitions are mutually recursive, and for reasons that don't apply to a pure language like Haskell, these have to be marked explicitly by the programmer."

sampo11y ago

Hmm, yes.

Depends on whether /u/hencq asked about why rec is needed, or why and is needed.

I answered above, why rec. And you answered why an explicit grouping of mutually recursive functions using and is needed. And true, this is needed for type inference. And even though Standard ML does not need rec, it does need and.

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