Language.PureScript.TypeChecker.Entailment

Type class entailment

Documentation

type InstanceContext = Map QualifiedBy (Map (Qualified (ProperName 'ClassName)) (Map (Qualified Ident) (NonEmpty NamedDict)))

The InstanceContext tracks those constraints which can be satisfied.

data SolverOptions

Options for the constraint solver

Constructors

SolverOptions

Fields

• solverShouldGeneralize :: Bool

  Should the solver be allowed to generalize over unsolved constraints?

• solverDeferErrors :: Bool

  Should the solver be allowed to defer errors by skipping constraints?

replaceTypeClassDictionaries :: forall m. (MonadState CheckState m, MonadError MultipleErrors m, MonadWriter MultipleErrors m, MonadSupply m) => Bool -> Expr -> m (Expr, [(Ident, InstanceContext, SourceConstraint)])

Replace type class dictionary placeholders with inferred type class dictionaries

newDictionaries :: MonadState CheckState m => [(Qualified (ProperName 'ClassName), Integer)] -> Qualified Ident -> SourceConstraint -> m [NamedDict]

Add a dictionary for the constraint to the scope, and dictionaries for all implied superclass instances.

entails

Arguments

:: forall m. (MonadState CheckState m, MonadError MultipleErrors m, MonadWriter MultipleErrors m, MonadSupply m)

=> SolverOptions

Solver options

-> SourceConstraint

The constraint to solve

-> InstanceContext

The contexts in which to solve the constraint

-> [ErrorMessageHint]

Error message hints to apply to any instance errors

-> WriterT (Any, [(Ident, InstanceContext, SourceConstraint)]) (StateT InstanceContext m) Expr

Check that the current set of type class dictionaries entail the specified type class goal, and, if so, return a type class dictionary reference.