[Haskell-cafe] TH clause Pat selection

Brian Lewis brian at lorf.org
Thu Jun 20 00:23:11 CEST 2013

I want to use TH to generate functions like
foo :: c -> h
foo ... = ...
foo ... = ...
from lists of pairs :: [(c, h)]

For example, $(genFoo ''Int ''Bool [(0,False), (1,True)])
would generate
foo 0 = False
foo 1 = True

The problem is, I don't know how to generate the function's clauses.
"foo 0 = ..." seems to be a LitP pattern. But "foo True = ..." seems to
be a ConP pattern. The appropriate pattern depends on type c.

Here's code with more explanation and examples:

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