diff options
Diffstat (limited to 'libraries')
| -rw-r--r-- | libraries/ghc-prim/GHC/Types.hs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/libraries/ghc-prim/GHC/Types.hs b/libraries/ghc-prim/GHC/Types.hs index 6f9e09fdfb..736ea3dbfa 100644 --- a/libraries/ghc-prim/GHC/Types.hs +++ b/libraries/ghc-prim/GHC/Types.hs @@ -193,7 +193,11 @@ inside GHC, to change the kind and type. -- | Lifted, heterogeneous equality. By lifted, we mean that it -- can be bogus (deferred type error). By heterogeneous, the two --- types @a@ and @b@ might have different kinds. +-- types @a@ and @b@ might have different kinds. Because @~~@ can +-- appear unexpectedly in error messages to users who do not care +-- about the difference between heterogeneous equality @~~@ and +-- homogeneous equality @~@, this is printed as @~@ unless +-- @-fprint-equality-relations@ is set. class a ~~ b -- See also Note [The equality types story] in TysPrim |