GHC.Tc.Utils.Monad

Set up the typechecking environment.

Initialise the type checker monad for use in GHCi.

Do it flag is true

Update the external package state. Returns the second result of the modifier function.

This is an atomic operation and forces evaluation of the modified EPS in order to avoid space leaks.

Update the external package state.

This is an atomic operation and forces evaluation of the modified EPS in order to avoid space leaks.

How should TcM plugins be handled when initialising of the typechecker? See Note [Stop TcM plugins after desugaring].

Usage:

1. If you want to typecheck then desugar, use StartAndKeepRunningTcMPlugins. This will ensure TcM plugins are kept running for the benefit of the pattern-match checker, and shut down after desugaring.

2. If you only want to typecheck and not desugar, use StartAndStopTcMPlugins.

3. If a prior operation has started TcM plugins, you can use UseRunningTcMPlugins to avoid re-initialising the plugins, for example in initTc.

4. If you don't care about TcM plugins at all, you can use NoTcMPlugins.

Initialise all TcM plugins, run the inner action, then run both their "post-tc" and "shutdown" actions.

Dump if the given DumpFlag is set.

Unconditionally dump some trace output

Certain tests (T3017, Roles3, T12763 etc.) expect part of the output generated by `-ddump-types` to be in PprUser style. However, generally we want all other debugging output to use PprDump style. We PprUser style if useUserStyle is True.

Like logInfoTcRn, but for user consumption

tcCollectingUsage thing_inside runs thing_inside and returns the usage information which was collected as part of the execution of thing_inside. Careful: tcCollectingUsage thing_inside itself does not report any usage information, it's up to the caller to incorporate the returned usage information into the larger context appropriately.

tcScalingUsage mult thing_inside runs thing_inside and scales all the usage information by mult.

Drop elements of the input that fail, so the result list can be shorter than the argument list

Apply the function to all elements on the input list If all succeed, return the list of results Otherwise fail, propagating all errors

The accumulator is not updated if the action fails

A variation of addDiagnostic that takes a function to produce a TcRnDsMessage given some additional context about the diagnostic.

Display a warning if a condition is met.

Display a warning if a condition is met.

Display a diagnostic if a condition is met.

Display a diagnostic in the current context.

Display a diagnostic in a given context.

Display a diagnostic for the current source location, taken from the TcRn monad.

Display a diagnostic for a given source location.

Creates an EvBindsVar incapable of holding any bindings. It still tracks covar usages (see comments on ebv_needs in GHC.Tc.Types.Evidence), thus must be made monadically

Throw out any constraints emitted by the thing_inside

The name says it all. The returned TcLevel is the *inner* TcLevel.

Put a value in a coercion hole

Adds the given modFinalizers to the global environment and set them to use the current local environment.

Mark that safe inference has failed See Note [Safe Haskell Overlapping Instances Implementation] although this is used for more than just that failure case.

Figure out the final correct safe haskell mode

Switch instances to safe instances if we're in Safe mode.

Run an IfG (top-level interface monad) computation inside an existing TcRn (typecheck-renaming monad) computation by initializing an IfGblEnv based on TcGblEnv.

Initialize interface typechecking, but with a NameShape to apply when typechecking top-level OccNames (see lookupIfaceTop)

initIfaceLoad can be used when there's no chance that the action will call typecheckIface when inside a module loop and hence tcIfaceGlobal.

This is used when we are doing to call typecheckModule on an ModIface, if it's part of a loop with some other modules then we need to use their IORef TypeEnv vars when typechecking but crucially not our own.

Run thing_inside in an interleaved thread. It shares everything with the parent thread, so this is DANGEROUS.

It throws an error if the computation fails

It's used for lazily type-checking interface signatures, which is pretty benign.

See Note [Masking exceptions in forkM]

A convenient wrapper for taking a MaybeErr SDoc a and throwing an exception if it is an error.

Get the next cost centre index associated with a given name.

See getCCIndexM.

Lift a computation from the dedicated zonking monad ZonkM to the full-fledged TcM monad.