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Check a single pattern binding (let)

Check a matchgroup (case, functions, etc.)

Check whether any part of pattern match checking is enabled (does not matter whether it is the redundancy check or the exhaustiveness check).

Generate a simple equality when checking a case expression: case x of { matches } When checking matches we record that (x ~ y) where y is the initial uncovered. All matches will have to satisfy this equality.

Generate equalities when checking a case expression: case x of { p1 -> e1; ... pn -> en } When we go deeper to check e.g. e1 we record two equalities: (x ~ y), where y is the initial uncovered when checking (p1; .. ; pn) and (x ~ p1).

Returns True if the argument Type is a fully saturated application of a closed type constructor.

Closed type constructors are those with a fixed right hand side, as opposed to e.g. associated types. These are of particular interest for pattern-match coverage checking, because GHC can exhaustively consider all possible forms that values of a closed type can take on.

Note that this function is intended to be used to check types of value-level patterns, so as a consequence, the Type supplied as an argument to this function should be of kind Type.

Get rid of *outermost* (or toplevel) * type function redex * data family redex * newtypes

Behaves exactly like topNormaliseType_maybe, but instead of returning a coercion, it returns useful information for issuing pattern matching warnings. See Note [Type normalisation for EmptyCase] for details.