diff options
Diffstat (limited to 'testsuite/tests/indexed-types/should_run/T2985.hs')
| -rw-r--r-- | testsuite/tests/indexed-types/should_run/T2985.hs | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_run/T2985.hs b/testsuite/tests/indexed-types/should_run/T2985.hs new file mode 100644 index 0000000000..6ae6e12c50 --- /dev/null +++ b/testsuite/tests/indexed-types/should_run/T2985.hs @@ -0,0 +1,13 @@ +{-# LANGUAGE TypeFamilies, UndecidableInstances #-} +{-# OPTIONS_GHC -Wnot #-} + +module Main where + +-- See http://article.gmane.org/gmane.comp.lang.haskell.general/16796 +-- and Trac #2985 + +instance (Num a, Num b, a ~ b) => Num (a,b) where + (x,y) * (u,v) = (x*u-y*v, x*v+y*u) + +test1 = (1,1) * (2,2) +main = print test1 |