Better document TypeRep patterns
authorBen Gamari <bgamari.foss@gmail.com>
Wed, 13 Sep 2017 16:23:47 +0000 (12:23 -0400)
committerBen Gamari <ben@smart-cactus.org>
Wed, 13 Sep 2017 20:45:49 +0000 (16:45 -0400)
commitf9bf621caf2fc17d829dee0ee48b204144927e72
tree2cd9ffe866fdfe6a25dcf090fa21c5f7a74b5d2c
parent2fe6f6baba70de071c391bccc77197ab4f81064d
Better document TypeRep patterns

As pointed out in #14199 these are rather non-trivial; extra
documentation is in order.

[skip ci]

Test Plan: Read it

Reviewers: dfeuer, austin, hvr

Subscribers: rwbarton, thomie

GHC Trac Issues: #14199

Differential Revision: https://phabricator.haskell.org/D3943
libraries/base/Data/Typeable/Internal.hs