[Haskell-cafe] Functional programming and William Lawvere's notion of "variable sets"(vs topos of "static sets") in a Topos ...

Vasili I. Galchin vigalchin at gmail.com
Sat Aug 2 06:28:41 UTC 2014

Hello Haskellers,

     I have been re-reading William Lawvere's description of "variable
sets" (a functor category) in "a elementary topoi" on a discrete
poset/preset vs a "abstract sets" in the topos of abstract sets . In
Haskell( and other FPLs .. ) aren't "pure" computations just over the
topos of abstract sets and "mutable" /"time-varying/stateful"
computations aren't just "variable sets" (i.e. a functor over a
discrete preset-poset)?? Please forgive my bad English :-( If
uncertain aboyt my Englsih, please say so.

Kind regards,


P.S. Yes I am familiar with Eugenio Moggi's papers on using monads for
stateful computations ..

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