#3012: A little deriving for GADTs
---------------------------------+------------------------------------------
Reporter: guest | Owner:
Type: feature request | Status: closed
Priority: normal | Milestone: 6.12.1
Component: Compiler | Version: 6.10.1
Severity: minor | Resolution: fixed
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
---------------------------------+------------------------------------------
Changes (by simonpj):
* status: new => closed
* resolution: => fixed
Comment:
OK it's done
{{{
Thu Jul 23 06:01:45 PDT 2009 [email protected]
* Fix Trac #3012: allow more free-wheeling in standalone deriving
Ignore-this: 357580b9388ccbe1da3c1da3ba90e456
In standalone deriving, we now do *not* check side conditions.
We simply generate the code and typecheck it. If there's a type
error, it's the programmer's problem.
This means that you can do 'deriving instance Show (T a)', where
T is a GADT, for example, provided of course that the boilerplate
code does in fact typecheck.
I put some work into getting a decent error message. In particular
if there's a type error in a method, GHC will show the entire code
for that method (since, after all, the user did not write it).
Most of the changes are to achieve that goal.
Still to come: changes in the documentation.
M ./compiler/typecheck/TcClassDcl.lhs -1 +1
M ./compiler/typecheck/TcDeriv.lhs -25 +27
M ./compiler/typecheck/TcEnv.lhs -2 +3
M ./compiler/typecheck/TcInstDcls.lhs -8 +22
M ./compiler/typecheck/TcMatches.lhs -1 +2
M ./compiler/typecheck/TcRnMonad.lhs -21 +31
M ./compiler/typecheck/TcRnTypes.lhs -6 +9
M ./compiler/utils/Outputable.lhs -3 +3
}}}
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3012#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
