What does the Haskell function forall do and where is it defined? -


i'm reading a little lens starter tutorial , use seemingly magical function forall this:

>>> forall $ \tuple -> view _1 tuple == fst tuple true

what function , more importantly package from. can't find using hoogle, etc.

haha, embarrassed author here.

i invented forall mime quickcheck , make intuitive sense, not executable. in defense, took inspiration little schemer happily introduces syntax , semantics far before they're executable in order build intuition practice.

except, of course, forall not executable @ , has lead lot of confusion.

so, suggestion curious investigate quickcheck stand-in forall. suggestion myself, now carried out, edit tutorial note artistic license there.

sorry trouble.


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