Levity polymorphism

This is a status page for levity polymorphism, as described in the ​Levity Polymorphism paper.

See also UnliftedDataTypes

Tickets

Use Keyword = LevityPolymorphism to ensure that a ticket ends up on these lists.

Open Tickets:

#11715

Constraint vs *

#12708

RFC: Representation polymorphic Num

#12980

Unlifted class method rejected

#12989

($) can have a more general type

#13105

Allow type families in RuntimeReps

#13233

typePrimRep panic while compiling GHC with profiling

#13592

Newtype type class with compiler generated instances

#13595

Should ‘coerce’ be levity polymorphic?

#14185

Non-local bug reporting around levity polymorphism

#14196

Replace ArrayArray# with either UnliftedArray# or Array#

#14765

Levity polymorphism panic

#14917

Allow levity polymorphism in binding position

#15532

Relaxing Levity-Polymorphic Binder Check for Lifted vs Unlifted pointers

#15883

GHC panic: newtype F rep = F (forall (a :: TYPE rep). a)

Closed Tickets:

#11431

GHC instantiates levity-polymorphic type variables with foralls

#11465

Eliminate check_lifted check in TcValidity

#11471

Kind polymorphism and unboxed types: bad things are happening

#11473

Levity polymorphism checks are inadequate

#11714

Kind of (->) type constructor is overly constrained

#11724

Must check for representation polymorphism in datatype declarations

#11736

Allow unsaturated uses of unlifted types in Core

#11786

Need -fno-print-explicit-runtime-reps to work on IfaceType, else RuntimeRep leaks

#12668

Program that fails Core Lint terribly

#12670

Representation polymorphism validity check is too strict

#12709

GHC panic

#12718

Segmentation fault, runtime representation polymorphism

#12809

TYPE 'UnboxedTupleRep is still a lie

#12901

Levity polymorphic expressions mustn't be floated out

#12905

Core lint failure with pattern synonym and levity polymorphism

#12911

Levity polymorphism check eliminates non-levity-polymorphic data constructor

#12973

No levity-polymorphic arguments

#12987

Core lint error with levity polymorphism

#13202

Levity polymorphism panic in GHCi

#13244

Error Dealing with Unboxed Types and Type Families

#13275

ghci ignores -fprint-explicit-runtime-reps

#13343

Levity polymorphism-related GHC panic: expectJust zonkTcTyVarToVar

#13435

Segfaults on levity-polymorphic type class

#13458

Panic with unsafeCoerce and -dcore-lint

#13509

Perplexing type error with unboxed tuples

#13601

GHC errors but hangs

#13603

Can't resolve levity polymorphic superclass

#13929

GHC panic with levity polymorphism

#13955

Backpack does not handle unlifted types

#13963

Runtime representation confusingly displayed

#14555

GHC Panic with TypeInType / levity polymorphism

#14561

Panic on levity polymorphic very unsafe coerce

#14563

GHC Panic with TypeInType / levity polymorphism

#15180

Make Control.Exception.throw levity polymorphic

#15181

Levity Polymorphic type signatures in GHC.Prim