Agda-2.5.1.2: A dependently typed functional programming language and proof assistant

Agda.TypeChecking.InstanceArguments

Synopsis

# Documentation

Compute a list of instance candidates. Nothing if type is a meta, error if type is not eligible for instance search.

findInScope :: MetaId -> Maybe [Candidate] -> TCM () Source #

findInScope m (v,a)s tries to instantiate on of the types as of the candidate terms vs to the type t of the metavariable m. If successful, meta m is solved with the instantiation of v. If unsuccessful, the constraint is regenerated, with possibly reduced candidate set. The list of candidates is equal to Nothing when the type of the meta wasn't known when the constraint was generated. In that case, try to find its type again.

findInScope' :: MetaId -> [Candidate] -> TCM (Maybe ([Candidate], Maybe MetaId)) Source #

Result says whether we need to add constraint, and if so, the set of remaining candidates and an eventual blocking metavariable.

insidePi :: Type -> (Type -> TCM a) -> TCM a Source #

Precondition: type is spine reduced and ends in a Def or a Var.

A meta _M is rigidly constrained if there is a constraint _M us == D vs, for inert D. Such metas can safely be instantiated by recursive instance search, since the constraint limits the solution space.

Returns True if one of the arguments of t is a meta which isn’t rigidly constrained. Note that level metas are never considered rigidly constrained (#1865).

filterResetingState :: MetaId -> [Candidate] -> (Candidate -> TCM YesNoMaybe) -> TCM [Candidate] Source #

Apply the computation to every argument in turn by reseting the state every time. Return the list of the arguments giving the result True.

If the resulting list contains exactly one element, then the state is the same as the one obtained after running the corresponding computation. In all the other cases, the state is reseted.

Constructors

 Yes No Maybe

Instances

 Source # Methods Source # MethodsshowList :: [YesNoMaybe] -> ShowS #

checkCandidates :: MetaId -> Type -> [Candidate] -> TCM (Maybe [Candidate]) Source #

Given a meta m of type t and a list of candidates cands, checkCandidates m t cands returns a refined list of valid candidates.

To preserve the invariant that a constructor is not applied to its parameter arguments, we explicitly check whether function term we are applying to arguments is a unapplied constructor. In this case we drop the first conPars arguments. See Issue670a. Andreas, 2013-11-07 Also do this for projections, see Issue670b.