Pull requests from GitHub

This is a batch of small pull requests from GitHub.

Specifically:

• https://github.com/ghc/ghc/pull/243
• https://github.com/ghc/ghc/pull/247
• https://github.com/ghc/ghc/pull/248
• https://github.com/ghc/ghc/pull/249
• https://github.com/ghc/ghc/pull/250
• https://github.com/ghc/ghc/pull/251