[Haskell-cafe] Can I allow multiple rigid type variables?

Brandon Allbery allbery.b at gmail.com
Fri Jan 13 16:24:04 UTC 2017

On Fri, Jan 13, 2017 at 12:55 AM, Cody Goodman <
codygman.consulting at gmail.com> wrote:

> What exactly does (as ++ bs) ~ (bs ++ as) mean?

It tells the typechecker that the parameters to type-level (++) can be
swapped and still produce the same result type (that is, type-level (++) is

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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