[Haskell-cafe] Object Oriented programming for Functional Programmers

David Thomas davidleothomas at gmail.com
Fri Jan 4 13:27:51 CET 2013

On Sun, Dec 30, 2012 at 1:27 PM, Brandon Allbery <allbery.b at gmail.com>wrote:

> [T]he "Monad m =>" in the signature really means "hey, compiler, pass me
> the appropriate implementation of Monad so I can figure out what I'm doing
> with this type m".  It's not a built in table, it's a hidden parameter.
Well, "hidden" - it *is* right there in the type signature still, it just
doesn't *look* like an argument.

It also might be optimized away in static cases (certainly, it *could*
happen, whether does or is even worthwhile is another question).
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