Re: [Haskell-cafe] Haskell-Cafe Digest, Vol 217, Issue 16

On Sep 17, 2021, at 1:11 PM, Tom Ellis wrote:

On Fri, Sep 17, 2021 at 05:02:09PM +0000, Richard Eisenberg wrote:

...

For me, coming from a mostly Java background (but with a healthy dollop of functional programming thrown in the mix -- but no Haskell), the phrase that unlocked monads was "programmable semicolon".

I'm curious what "unlock" means here.

It's hard to be sure, as this was ~10 years ago, but I think it was about motivation for me. Specifically: why do we need more than one monad, IO. I understood that Haskell functions were pure, and thus could produce no side effects. So we needed to have *some* way of having a program interact with the world. This way was the set of functions that work in the IO monad. These operations need a way of interacting with pure code (i.e. `return`) and some way of sequencing (i.e. >>=). This was all clear enough. What I didn't understand is why there was a typeclass to capture this or why we needed other monads -- until I associated "monad" with "programmable semicolon". At that point, I realized that the idea is very powerful. Richard

Do you mean you could understand the definition of the monad class after coming across "programmable semicolon" but not before? Or do you mean you understood the *purpose* of monads, but not necessarily how one would go about implementing them? Or something else? _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.