diff options
Diffstat (limited to 'compiler/deSugar/Check.hs')
| -rw-r--r-- | compiler/deSugar/Check.hs | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/compiler/deSugar/Check.hs b/compiler/deSugar/Check.hs index 0c653da2b2..1495280f94 100644 --- a/compiler/deSugar/Check.hs +++ b/compiler/deSugar/Check.hs @@ -2118,15 +2118,22 @@ pmcheckHd (p@(PmLit l)) ps guards -- no information is lost -- LitCon -pmcheckHd (PmLit l) ps guards (va@(PmCon {})) (ValVec vva delta) +pmcheckHd p@PmLit{} ps guards va@PmCon{} (ValVec vva delta) = do y <- liftD $ mkPmId (pmPatType va) - let tm_state = extendSubst y (PmExprLit l) (delta_tm_cs delta) + -- Analogous to the ConVar case, we have to case split the value + -- abstraction on possible literals. We do so by introducing a fresh + -- variable that is equated to the constructor. LitVar will then take + -- care of the case split by resorting to NLit. + let tm_state = extendSubst y (vaToPmExpr va) (delta_tm_cs delta) delta' = delta { delta_tm_cs = tm_state } - pmcheckHdI (PmVar y) ps guards va (ValVec vva delta') + pmcheckHdI p ps guards (PmVar y) (ValVec vva delta') -- ConLit -pmcheckHd (p@(PmCon {})) ps guards (PmLit l) (ValVec vva delta) +pmcheckHd p@PmCon{} ps guards (PmLit l) (ValVec vva delta) = do y <- liftD $ mkPmId (pmPatType p) + -- This desugars to the ConVar case by introducing a fresh variable that + -- is equated to the literal via a constraint. ConVar will then properly + -- case split on all possible constructors. let tm_state = extendSubst y (PmExprLit l) (delta_tm_cs delta) delta' = delta { delta_tm_cs = tm_state } pmcheckHdI p ps guards (PmVar y) (ValVec vva delta') |