GHC.HsToCore.PmCheck

Documentation

checkSingle :: DynFlags -> DsMatchContext -> Id -> Pat GhcTc -> DsM ()

Check a single pattern binding (let) for exhaustiveness.

checkMatches

Arguments

:: DsMatchContext

Match context, for warnings messages

-> [Id]

Match variables, i.e. x and y above

-> [LMatch GhcTc (LHsExpr GhcTc)]

List of matches

-> DsM [Deltas]

One covered Deltas per RHS, for long distance info.

Check a list of syntactic matches (part of case, functions, etc.), each with a pat and one or more grhss:

  f x y | x == y    = 1   -- match on x and y with two guarded RHSs
        | otherwise = 2
  f _ _             = 3   -- clause with a single, un-guarded RHS

Returns one Deltas for each GRHS, representing its covered values, or the incoming uncovered Deltas (from getPmDeltas) if the GRHS is inaccessible. Since there is at least one grhs per match, the list of Deltas is at least as long as the list of matches.

checkGuardMatches

Arguments

:: HsMatchContext GhcRn

Match context, for warning messages

-> GRHSs GhcTc (LHsExpr GhcTc)

The GRHSs to check

-> DsM [Deltas]

Covered Deltas for each RHS, for long distance info

Exhaustive for guard matches, is used for guards in pattern bindings and in MultiIf expressions. Returns the Deltas covered by the RHSs.

isMatchContextPmChecked :: DynFlags -> Origin -> HsMatchContext id -> Bool

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

addTyCsDs :: Origin -> Bag EvVar -> DsM a -> DsM a

Add in-scope type constraints if the coverage checker might run and then run the given action.

addScrutTmCs :: Maybe (LHsExpr GhcTc) -> [Id] -> DsM a -> DsM a

Add equalities for the scrutinee to the local DsM environment when checking a case expression: case e of x { matches } When checking matches we record that (x ~ e) where x is the initial uncovered. All matches will have to satisfy this equality.