PUBLIC
Hi,
I'd like to hijack some syntax (like string literals or list patterns) for my
own use, and I thought a low-tech way of doing that is to transform the
ParsedModule before typechecking. For example, if I have a function `uncons ::
Array a -> Maybe (a, Array a)`, I can rewrite the pattern `[x1, x2, x3]` into
the view pattern `(uncons -> Just (x1, (uncons -> Just (x2, (uncons -> Just
(x3, (uncons -> Nothing)))))))` and let the normal GHC type checker take over
from here.
This is working for me so far, except for one problem: the typechecker now
complains that the `ViewPatterns` language extension is not turned on. I would
like to make the view patterns coming from my ParsedModule rewriter to be
exempt from this check (but of course still require the `ViewPatterns`
extension for user-originating code). Is there a way to do that? Or would I be
better off checking for user-originating view patterns myself before the
rewrite and then changing the `DynFlags` to always enable view patterns for
typechecking?
Thanks,
Gergo
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