Could it be so that you can shortcut in the expected order (left to right)?
Left associative:
a && b && c = (a && b) && c which means going into a && b, which means
going into a, and if it is False, then going up in the expression tree.
If it is right associative:
a && b && c = a && (b && c), which means going into a, and if it is False,
you are done.
If you have a conjunction of n booleans, the complexity of evaluating this
expression is linear with respect to the position of the first False (in
the case of &&). In the left-associative case, it is linear in the number
of &&s.
Just a guess. But you got me interested now.
Does anyone have the real explanation?
Cheers,
Ivan
On Thu, 11 Apr 2019 at 22:13, Richard Eisenberg
Hi café,
Why are && and || in the Prelude right-associative? This contradicts my expectation and the way these work in other languages. That said, I can't think of any harm in it. This came up from a question asked by a student, and I have no idea why the design is this way.
Thanks, Richard _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.