Commit 3cec5683 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com

Comment on the commoning up of CoPats in Match

parent 133d0902
......@@ -745,6 +745,10 @@ sameGroup (PgN l1) (PgN l2) = True -- Needs conditionals
sameGroup (PgNpK l1) (PgNpK l2) = l1==l2 -- Order is significant
-- See Note [Order of n+k]
sameGroup (PgCo t1) (PgCo t2) = t1 `coreEqType` t2
-- CoPats are in the same goup only if the type of the
-- enclosed pattern is the same. The patterns outside the CoPat
-- always have the same type, so this boils down to saying that
-- the two coercions are identical.
sameGroup _ _ = False
patGroup :: Pat Id -> PatGroup
......
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