diff options
| author | Adam Gundry <adam@well-typed.com> | 2015-05-04 15:30:37 +0100 |
|---|---|---|
| committer | Adam Gundry <adam@well-typed.com> | 2015-05-04 15:37:56 +0100 |
| commit | 4efa421327cf127ebefde59b2eece693e37dc3c6 (patch) | |
| tree | ad98439468450a0d9b39c80d1a8e443e34b0445e /testsuite/tests/th/T10306.hs | |
| parent | 2f6a0ac7061c59ed68a6dd5a2243e3e690acbd5f (diff) | |
| download | haskell-4efa421327cf127ebefde59b2eece693e37dc3c6.tar.gz | |
Permit empty closed type families
Fixes #9840 and #10306, and includes an alternative resolution to #8028.
This permits empty closed type families, and documents them in the user
guide. It updates the Haddock submodule to support the API change.
Test Plan: Added `indexed-types/should_compile/T9840` and updated
`indexed-types/should_fail/ClosedFam4` and `th/T8028`.
Reviewers: austin, simonpj, goldfire
Reviewed By: goldfire
Subscribers: bgamari, jstolarek, thomie, goldfire
Differential Revision: https://phabricator.haskell.org/D841
GHC Trac Issues: #9840, #10306
Diffstat (limited to 'testsuite/tests/th/T10306.hs')
| -rw-r--r-- | testsuite/tests/th/T10306.hs | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/testsuite/tests/th/T10306.hs b/testsuite/tests/th/T10306.hs new file mode 100644 index 0000000000..b93114b61c --- /dev/null +++ b/testsuite/tests/th/T10306.hs @@ -0,0 +1,14 @@ +{-# LANGUAGE TemplateHaskell, TypeFamilies #-} + +module T10306 where + +import Language.Haskell.TH +import GHC.TypeLits + +-- Attempting to reify a built-in type family like (+) previously +-- caused a crash, because it has no equations +$(do x <- reify ''(+) + case x of + FamilyI (ClosedTypeFamilyD _ _ _ []) _ -> return [] + _ -> error $ show x + ) |