Better error message when UnboxedTuples isn't enabled
Motivation
Suppose we have the following program:
main = case (# 10, 11 #) of
(# foo, bar #) -> print (foo,bar)
GHC will fail to compile with:
Test.hs:2:5: error: Parse error in pattern: #foo
|
2 | (# foo, bar #) -> print (foo,bar)
| ^^^^^^^^^
Notice that GHC removes the spaces between "#" and "foo", which can be misleading.
Proposal
If the pattern starts with "#", maybe suggest to enable UnboxedTuples
.
Don't remove the spaces between "#" and "foo" in the parse error.