Language extensions - backwards compatibility
ia at stryx.demon.co.uk
Thu Jan 28 18:38:27 EST 2010
I'm looking for a way of specifying language extensions in a way which will
work in all versions of GHC from 6.4 onwards.
GHC 6.4 does not support the LANGUAGE pragma. Specifying language options in
the OPTIONS_GHC pragma starts to produce deprecation warnings in 6.10, and will
presumably eventually fail altogether.
Any sort of preprocessing at the beginning of a file appears to insert enough
noise to inhibit recognition of file-header pragmas. (Cpphs doesn't appear to
help here.) Attempting preprocessing inside a leading OPTIONS_GHC pragma fails
because it apparently attempts to interpret the pragma *before* invoking the
The only remaining option I can see is to have a completely separate version of
the file for GHC 6.4. Have I missed anything?
Iain Alexander ia at stryx.demon.co.uk
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