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| author | mniip <mniip@mniip.com> | 2019-01-20 20:48:13 -0500 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-08-07 10:18:07 -0400 |
| commit | 2073745c70d830373c67b908e5c42d3cd18c057a (patch) | |
| tree | 5f89a76cc92a05c75183223c3878d7446945758c /docs/users_guide/glasgow_exts.rst | |
| parent | 6f116005a144b3f09381e0a5967a364eb57a5aa5 (diff) | |
| download | haskell-2073745c70d830373c67b908e5c42d3cd18c057a.tar.gz | |
Add a -fprint-axiom-incomps option (#15546)
Supply branch incomps when building an IfaceClosedSynFamilyTyCon
`pprTyThing` now has access to incomps. This also causes them to be
written out to .hi files, but that doesn't pose an issue other than a
more faithful bijection between `tyThingToIfaceDecl` and `tcIfaceDecl`.
The machinery for displaying axiom incomps was already present but not
in use. Since this is now a thing that pops up in ghci's :info the
format was modified to look like a haskell comment.
Documentation and a test for the new feature included.
Test Plan: T15546
Reviewers: simonpj, bgamari, goldfire
Reviewed By: simonpj
Subscribers: rwbarton, carter
GHC Trac Issues: #15546
Differential Revision: https://phabricator.haskell.org/D5097
Diffstat (limited to 'docs/users_guide/glasgow_exts.rst')
| -rw-r--r-- | docs/users_guide/glasgow_exts.rst | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/docs/users_guide/glasgow_exts.rst b/docs/users_guide/glasgow_exts.rst index c46812baeb..513a787de2 100644 --- a/docs/users_guide/glasgow_exts.rst +++ b/docs/users_guide/glasgow_exts.rst @@ -8047,6 +8047,9 @@ other hand, the two equations are compatible. Thus, GHC can ignore the first equation when looking at the second. So, ``G a`` will simplify to ``a``. +Incompatibilities between closed type family equations can be displayed +in :ghci-cmd:`:info` when :ghc-flag:`-fprint-axiom-incomps` is enabled. + However see :ref:`ghci-decls` for the overlap rules in GHCi. .. _type-family-decidability: |