GHC.Tc.Solver.Monad

This variant of runTcS will immediately fail upon encountering an insoluble ct. See Note [Speeding up valid hole-fits]. Its one usage site does not need the ev_binds, so we do not return them.

A variant of runTcS that takes and returns an InertSet for later resumption of the TcS session.

Emit a warning within the TcS monad at the location given by the CtLoc.

This can deal only with equality constraints.

A quantified constraint, also called a "local instance" (a simplified version of ClsInst).

See Note [Quantified constraints] in GHC.Tc.Solver.Solve

The mode for the constraint solving monad.

CanonicalEvidence says whether a piece of evidence has a singleton type; For example, given (d1 :: C Int), will any other (d2 :: C Int) do equally well? See Note [Coherence and specialisation: overview] above, and Note [Desugaring non-canonical evidence] in GHC.HsToCore.Binds

Create a new Wanted constraint holding a coercion hole for an equality between the two types at the given Role.

Create a new Wanted constraint, potentially looking up non-equality constraints in the cache instead of creating a new one from scratch.

Deals with both equality and non-equality constraints.

Create a new Wanted constraint.

Deals with both equality and non-equality constraints.

Does not attempt to re-use non-equality constraints that already exist in the inert set.

Create a new Wanted constraint holding an evidence variable.

Don't use this for equality constraints: use newWantedEq instead.

Make a new Id of the given type, bound (in the monad's EvBinds) to the given term

Equalities only

Dictionaries only

Checks if the depth of the given location is too much. Fails if it's too big, with an appropriate error message.

Retrieves all insoluble constraints from the inert set, specifically including Given constraints.

This consists of:

• insoluble equalities, such as Int ~# Bool;

• constraints that are custom type errors, of the form TypeError msg or Maybe (TypeError msg), but not constraints such as F x (TypeError msg) in which the type error is nested under a type family application,

• unsatisfiable constraints, of the form Unsatisfiable msg.

The inclusion of Givens is important for pattern match warnings, as we want to consider a pattern match that introduces insoluble Givens to be redundant (see Note [Pattern match warnings with insoluble Givens] in GHC.Tc.Solver).

Remove inert constraints from the InertCans, for use when a typechecker plugin wishes to discard a given.

Look up a dictionary inert.

Look up a solved inert.

Looks up a family application in the inerts.