Use better show instances for notes & rationals

[matthewkaney]

In the discussion from #807 it came up that the Show instance for notes is a bit confusing, because it exposes the structure of the Note type. I added a new show function that prints the numeric value followed by the note name. Here's what it looks like in the context of a pattern:

> n "c d6 20.75 -30"
(0>¼)|n: 0.0n (c5)
(¼>½)|n: 14.0n (d6)
(½>¾)|n: 20.75n (a6)
(¾>1)|n: -30.0n (fs2)

I also updated the Show instance for patterns to use the prettier rational representation (used by time spans) for rational values.

[matthewkaney]

Hmm... it looks like the stack run is failing to install the happy package, probably because the version it's installing (1.21.0) seems to be deprecated.

I don't really know anything about stack, or this specific build job, so if folks have advice, that would be appreciated!

[yaxu]

Thanks @mindofmatthew, this looks great. I wonder if the note name shouldn't be shown for non-integers?

I'm not sure what's going on with happy, it seems strange to have the latest version deprecated. Maybe it's best wait and see if that sorts itself out..

[yaxu]

Aside from the stack issue (which isn't particular to this PR), is this ready for merge?

[matthewkaney]

Yes, unless you (or anyone else) wants a different display for non-integer notes. I think the most accurate representation would be something like 2.7n (ds5 - 30 cents) but that's maybe too long? Happy to drop the pitch names from non-integers or add a symbol like +d5 or <ds5 to indicate when a number is in between pitches.

[yaxu]

Lets go with this for now, thanks!