View source for Upgrading packages/Updating to GHC 7

A list of common problems upgrading packages to GHC 7.

If you maintain packages, this is for you.

== -XMonoLocalBinds ==

If you use -XGADTs or -XTypeFamilies you get -XMonoLocalBinds, which says that local let/where bindings are not auto-generalised.  There's a blog post that explains the change, and what do to about it:

* http://hackage.haskell.org/trac/ghc/blog/LetGeneralisationInGhc7

== base 3 goes away ==

There is no base 3 now, after being deprecated for several years, so dependencies on base 3 won't compile with GHC 7.

== -fglasgow-exts is deprecated ==

-fglasgow-exts is deprecated, and no longer enables GADTs or TypeFamilies. Use individual language flags (or better yet, pragmas) instead.

== Quasiquotation data constructor modified ==

The QuasiQuoter constructor now takes four arguments instead of 2. (quoteType and quoteDec were added). One solution: use record syntax to set only the quoters you provide. This allows code to remain backwards compatible.

== Quasiquotation: [$foo|...|] -> [foo|...|] ==

Quasiquoter invocation no longer requires a leading dollar sign. The leading dollar is now allowed, but deprecated.

== Required library versions ==

A list of libraries and their earliest (known) GHC 7 ready version:

* network >= 2.2.1.8
* mtl >= 1.1.1.0
* quickcheck >= 2.3.0.2
* stringsearch >= 0.3.2