Safe Haskell	Safe-Infered

Agda.TypeChecking.MetaVars.Occurs

Contents

Getting rid of flexible occurrences

Synopsis

Documentation

data OccursCtx Source

Constructors

Flex	we are in arguments of a meta
Rigid	we are not in arguments of a meta but a bound var
StronglyRigid	we are at the start or in the arguments of a constructor
Irrel	we are in an irrelevant argument

Instances

Eq OccursCtx
Show OccursCtx

data UnfoldStrategy Source

Constructors

YesUnfold
NoUnfold

Instances

Eq UnfoldStrategy
Show UnfoldStrategy

defArgs :: UnfoldStrategy -> OccursCtx -> OccursCtx Source

unfold :: UnfoldStrategy -> Term -> TCM (Blocked Term)Source

weakly :: OccursCtx -> OccursCtx Source

Leave the strongly rigid position.

strongly :: OccursCtx -> OccursCtx Source

abort :: OccursCtx -> TypeError -> TCM ()Source

type Vars = ([Nat], [Nat])Source

Distinguish relevant and irrelevant variables in occurs check.

goIrrelevant :: Vars -> Vars Source

allowedVar :: Nat -> Vars -> Bool Source

takeRelevant :: Vars -> [Nat]Source

underAbs :: Vars -> Vars Source

class Occurs t whereSource

Extended occurs check.

Methods

occurs :: UnfoldStrategy -> OccursCtx -> MetaId -> Vars -> t -> TCM tSource

Instances

Occurs LevelAtom
Occurs PlusLevel
Occurs Level
Occurs Sort
Occurs Type
Occurs Term
Occurs a => Occurs [a]
Occurs a => Occurs (Arg a)
Occurs a => Occurs (Abs a)
(Occurs a, Occurs b) => Occurs (a, b)

occursCheck :: MetaId -> Vars -> Term -> TCM Term Source

When assigning m xs := v, check that m does not occur in v and that the free variables of v are contained in xs.

Getting rid of flexible occurrences

prune :: MetaId -> Args -> [Nat] -> TCM PruneResult Source

prune m' vs xs attempts to remove all arguments from vs whose free variables are not contained in xs. If successful, m' is solved by the new, pruned meta variable and we return True else False.

hasBadRigid :: [Nat] -> Term -> Bool Source

hasBadRigid xs v = True iff one of the rigid variables in v is not in xs. Actually we can only prune if a bad variable is in the head. See issue 458.

data PruneResult Source

Constructors

NothingToPrune	the kill list is empty or only `False`s
PrunedNothing	there is no possible kill (because of type dep.)
PrunedSomething	managed to kill some args in the list
PrunedEverything	all prescribed kills where performed

Instances

Eq PruneResult
Show PruneResult

killArgs :: [Bool] -> MetaId -> TCM PruneResult Source

killArgs [k1,...,kn] X prunes argument i from metavar X if ki==True. Pruning is carried out whenever > 0 arguments can be pruned. True is only returned if all arguments could be pruned.

killedType :: [(Arg (String, Type), Bool)] -> Type -> ([Arg Bool], Type)Source

killedType [((x1,a1),k1)..((xn,an),kn)] b = ([k'1..k'n],t') (ignoring Arg). Let t' = (xs:as) -> b. Invariant: k'i == True iff ki == True and pruning the ith argument from type b is possible without creating unbound variables. t' is type t after pruning all k'i==True.

performKill :: [Arg Bool] -> MetaId -> Type -> TCM ()Source