[Pkg-haskell-maintainers] Bug#759503: haskell-language-python: FTBFS: missing happy

[Aaron M. Ucko]

Source: haskell-language-python
Version: 0.4.0-1
Severity: serious
Justification: fails to build from source

Builds of haskell-language-python in minimal environments (notably, on
the autobuilders) have been failing:

  hlibrary.setup: The program happy is required but it could not be found.
  make: *** [configure-ghc-stamp] Error 1
  /usr/share/cdbs/1/class/hlibrary.mk:111: recipe for target 'configure-ghc-stamp' failed

Please declare a build dependency on happy and confirm with pbuilder
or the like that you haven't missed any others.

Thanks!