[Haskell-cafe] Re: Why monoids will abide...

Andrzej Jaworski himself at poczta.nom.pl
Wed Jan 21 18:09:43 EST 2009

Category Theory should speak for itself and I am so glad you guys have seen the beauty of this

Yes, Mauro you are right: locally small Freyd categories correspond to monoidal structure of Arrows,
but the strength in this correspondence is as yet unknown to me. I disagree however with your doubts:
Arrows indeed are Monoids! [in the functor category (C^op) x C -> C with st, cost, ist.]

I will skip Monoid ubiquity in linguistics and its relevance to concurrency as not helpful in
learning Haskell.
(e.g. http://www.springerlink.com/content/7281243255312730/?p=4dd8bba881cd4ebe894d3b014f01b1ad&pi=7)

Instead I will issue a guarantee that the time invested in CT will pay also in system analysis,
particularly in combination with Haskell type classes, which together might be used for describing
real world processes and knowledge. Few have scratched the subject as yet but the pay-off is huge.

Let me also suggest to bestow the official  guru status on Dan Piponi and Heinrich Apfelmus:-)


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