compiler/typecheck

Contents:

• compiler/typecheck/ClsInst.hs
  • Note [Shortcut solving: overlap]
  • Note [KnownNat & KnownSymbol and EvLit]
  • Note [Fabricating Evidence for Literals in Backpack]
  • Note [Typeable (T a b c)]
  • Note [No Typeable for polytypes or qualified types]
  • Note [Typeable for Nat and Symbol]
  • Note [HasField instances]
• compiler/typecheck/FamInst.hs
  • Note [The type family instance consistency story]
  • Note [Checking family instance consistency]
  • Note [Checking family instance optimization]
  • Note [Home package family instances]
• compiler/typecheck/FunDeps.hs
  • Note [Coverage condition]
  • Note [Closing over kinds in coverage]
  • Note [The liberal coverage condition]
  • Note [Equality superclasses]
  • Note [Care with type functions]
• compiler/typecheck/Inst.hs
  • Note [Deep skolemisation]
  • Note [Handling boxed equality]
  • Note [Signature files and type class instances]
• compiler/typecheck/TcArrows.hs
  • Note [Arrow overview]
• compiler/typecheck/TcBackpack.hs
  • Note [Error reporting bad reexport]
  • Note [Blank hsigs for all requirements]
  • Note [Handling never-exported TyThings under Backpack]
• compiler/typecheck/TcBinds.hs
  • Note [Polymorphic recursion]
  • Note [Implicit parameter untouchables]
  • Note [Closed binder groups]
  • Note [Instantiate sig with fresh variables]
  • Note [Partial type signatures and generalisation]
  • Note [Quantified variables in partial type signatures]
  • Note [Validity of inferred types]
  • Note [Impedance matching]
  • Note [SPECIALISE pragmas]
  • Note [Typechecking pattern bindings]
• compiler/typecheck/TcCanonical.hs
  • Note [Canonicalization]
  • Top-level canonicalization
  • Note [The superclass story]
  • Note [Superclass loops]
  • Note [Eagerly expand given superclasses]
  • Note [Why adding superclasses can help]
  • Note [Danger of adding superclasses during solving]
  • Note [Equality superclasses in quantified constraints]
  • Note [Quantified constraints]
  • Note [Solving a Wanted forall-constraint]
  • Note [Solving a Given forall-constraint]
  • Note [Canonicalising equalities]
  • Note [FunTy and decomposing tycon applications]
  • Note [Unsolved equalities]
  • Note [Newtypes can blow the stack]
  • Note [Eager reflexivity check]
  • Note [Use canEqFailure in canDecomposableTyConApp]
  • Note [Decomposing equality]
  • Note [Decomposing newtypes at representational role]
  • Note [Decomposing TyConApps]
  • Note [Canonicalising type applications]
  • Note [Make sure that insolubles are fully rewritten]
  • Note [Do not decompose Given polytype equalities]
  • Note [Combining insoluble constraints]
  • Note [No top-level newtypes on RHS of representational equalities]
  • Note [Occurs check error]
  • Note [canCFunEqCan]
  • Note [Canonical orientation for tyvar/tyvar equality constraints]
  • Note [Equalities with incompatible kinds]
  • Note [Type synonyms and canonicalization]
  • Note [Rewriting with Refl]
  • Note [unifyWanted and unifyDerived]
• compiler/typecheck/TcClassDcl.hs
  • Note [Polymorphic methods]
  • Note [Silly default-method bind]
• compiler/typecheck/TcDeriv.hs
  • Note [Data decl contexts]
  • Note [Newtype deriving]
  • Note [Newtype deriving superclasses]
  • Note [Unused constructors and deriving clauses]
  • Note [Newtype deriving and unused constructors]
  • Note [Staging of tcDeriving]
  • Note [Why we don’t pass rep_tc into deriveTyData]
  • Note [Avoid RebindableSyntax when deriving]
  • Note [Flattening deriving clauses]
  • Note [tc_args and tycon arity]
  • Note [Unify kinds in deriving]
  • Note [Unification of two kind variables in deriving]
  • Note [Eta-reducing type synonyms]
  • Note [Looking up family instances for deriving]
  • Note [Deriving, type families, and partial applications]
  • Note [Recursive newtypes]
  • Note [Determining whether newtype-deriving is appropriate]
  • Note [GND and associated type families]
  • Note [Bindings for Generalised Newtype Deriving]
  • Note [DeriveAnyClass and default family instances]
  • Note [Deriving strategies]
  • Note [Deriving instances for classes themselves]
• compiler/typecheck/TcDerivInfer.hs
  • Note [Inferring the instance context]
  • Note [Getting base classes]
  • Note [Deriving and unboxed types]
  • Note [Superclasses of derived instance]
  • Note [Simplifying the instance context]
  • Note [Deterministic simplifyInstanceContexts]
  • Note [Overlap and deriving]
  • Note [Gathering and simplifying constraints for DeriveAnyClass]
  • Note [Error reporting for deriving clauses]
  • Note [Exotic derived instance contexts]
  • The bottom line
• compiler/typecheck/TcDerivUtils.hs
  • Note [Deriving and unused record selectors]
  • Note [Deriving any class]
  • Note [Check that the type variable is truly universal]
• compiler/typecheck/TcEnv.hs
  • Note [AFamDataCon: not promoting data family constructors]
  • Note [Don’t promote pattern synonyms]
  • Note [Extended defaults]
  • Note [Out of scope might be a staging error]
• compiler/typecheck/TcErrors.hs
  • Note [Deferring coercion errors to runtime]
  • Note [Suppressing error messages]
  • Note [Redundant constraints in instance decls]
  • Note [Given errors]
  • Note [Always warn with -fdefer-type-errors]
  • Note [Deferred errors for coercion holes]
  • Note [Do not report derived but soluble errors]
  • Note [Constraints include …]
  • Note [OutOfScope exact matches]
  • Note [Inaccessible code]
  • Note [Error messages for untouchables]
  • Note [Suppress redundant givens during error reporting]
  • Note [Insoluble occurs check wins]
  • Note [Expanding type synonyms to make types similar]
  • Note [Suggest adding a type signature]
  • Note [Disambiguating (X ~ X) errors]
  • Note [Reporting occurs-check errors]
  • Note [Non-injective type functions]
  • Note [Report candidate instances]
  • Note [discardProvCtxtGivens]
  • Note [Displaying potential instances]
  • Note [Flattening in error message generation]
  • Note [Kind arguments in error messages]
  • Note [Runtime skolems]
• compiler/typecheck/TcEvidence.hs
  • Note [TcCoercions]
  • Note [Coercion evidence only]
  • Note [Typeable evidence terms]
  • Note [Coercion evidence terms]
  • Note [EvBinds/EvTerm]
  • Note [Overview of implicit CallStacks]
  • Note [Free vars of EvFun]
• compiler/typecheck/TcExpr.hs
  • Note [Type-checking overloaded labels]
  • Note [Left sections]
  • Note [Typing rule for ($)]
  • Note [Typing rule for seq]
  • Note [Type of a record update]
  • Note [Implicit type sharing]
  • Note [Criteria for update]
  • Note [Data family example]
  • Outgoing invariants
  • Note [Mixed Record Field Updates]
  • Note [Visible type application for the empty list constructor]
  • Note [Required quantifiers in the type of a term]
  • Note [Visible type application zonk]
  • Note [tcSynArg]
  • Note [Push result type in]
  • Note [Partial expression signatures]
  • Note [Adding the implicit parameter to ‘assert’]
  • Note [tagToEnum#]
  • Note [Instantiating stupid theta]
  • Note [Lifting strings]
  • Local record selectors
  • Note [Disambiguating record fields]
  • Note [Splitting nested sigma types in mismatched function types]
  • Note [Finding the conflicting fields]
  • Note [Not-closed error messages]
  • Note [Checking closedness]
• compiler/typecheck/TcFlatten.hs
  • Note [The flattening story]
  • Why given-fsks, alone, doesn’t work
  • Why flatten-meta-vars, alone doesn’t work
  • Why is it right to treat fmv’s differently to ordinary unification vars?
  • Note [Unflattening can force the solver to iterate]
  • Note [The flattening work list]
  • Note [Flattener EqRels]
  • Note [Flattener CtLoc]
  • Note [Lazy flattening]
  • Note [Phantoms in the flattener]
  • Note [No derived kind equalities]
  • Note [Flattening]
  • Note [flatten_args performance]
  • Note [flatten_exact_fam_app_fully performance]
  • Note [Flattening synonyms]
  • Note [Flattening under a forall]
  • Note [Reduce type family applications eagerly]
  • Note [An alternative story for the inert substitution]
  • Note [Unflatten using funeqs first]
• compiler/typecheck/TcForeign.hs
  • Note [Don’t recur in normaliseFfiType’]
  • Note [FFI type roles]
  • Note [Newtype constructor usage in foreign declarations]
• compiler/typecheck/TcGenDeriv.hs
  • Note [Generating Ord instances]
  • Note [Game plan for deriving Ord]
  • Note [Use expectP]
  • Note [Read for empty data types]
  • Note [Newtype-deriving instances]
  • Note [Newtype-deriving trickiness]
  • Note [GND and QuantifiedConstraints]
  • Note [GND and ambiguity]
  • Note [Auxiliary binders]
• compiler/typecheck/TcGenFunctor.hs
  • Note [Deriving null]
  • Note [DeriveFoldable with ExistentialQuantification]
  • Note [FFoldType and functorLikeTraverse]
  • Note [Generated code for DeriveFoldable and DeriveTraversable]
  • Note [Phantom types with Functor, Foldable, and Traversable]
  • Note [EmptyDataDecls with Functor, Foldable, and Traversable]
• compiler/typecheck/TcGenGenerics.hs
  • Note [Requirements for deriving Generic and Rep]
  • Note [degenerate use of FFoldType]
  • Note [Generics and unlifted types]
  • Note [Generating a correctly typed Rep instance]
  • Note [Handling kinds in a Rep instance]
  • Note [Generics compilation speed tricks]
• compiler/typecheck/TcHoleErrors.hs
  • Note [Valid hole fits include …]
  • Note [Nested implications]
  • Note [Valid refinement hole fits include …]
  • Note [Relevant Constraints]
  • Note [Leaking errors]
• compiler/typecheck/TcHsSyn.hs
  • Note [The ZonkEnv]
  • Note [Un-unified unification variables]
  • Note [Skolems in zonkSyntaxExpr]
  • Note [Optimise coercion zonking]
  • Note [Sharing when zonking to Type]
  • Note [Zonking the LHS of a RULE]
• compiler/typecheck/TcHsType.hs
  • Note [Wildcards in visible type application]
  • Note [Dealing with :kind]
  • Note [Bidirectional type checking]
  • Note [Future-proofing the type checker]
  • Note [Wildcards in visible kind application]
  • Note [The Purely Kinded Type Invariant (PKTI)]
  • Note [mkAppTyM]
  • Note [saturateFamApp]
  • Note [GADT kind self-reference]
  • Note [Body kind of a HsForAllTy]
  • Note [Body kind of a HsQualTy]
  • Note [Inferring tuple kinds]
  • Note [Desugaring types]
  • Note [Kind of a type splice]
  • Help functions for type applications
  • Note [Keeping scoped variables in order: Explicit]
  • Note [Keeping scoped variables in order: Implicit]
  • Note [Recipe for checking a signature]
  • Note [The initial kind of a type constructor]
  • Note [No polymorphic recursion]
  • Note [Kind-checking tyvar binders for associated types]
  • Note [Kind variable ordering for associated types]
  • Note [Levels and generalisation]
  • Note [Kind generalisation]
  • Note [Kinds of quantified type variables]
  • Note [TyConBinders for the result kind signature of a data type]
  • Note [Avoid name clashes for associated data types]
  • Note [Extra-constraint holes in partial type signatures]
  • Note [Pattern signature binders]
• compiler/typecheck/TcInstDcls.hs
  • Note [How instance declarations are translated]
  • Note [Instances and loop breakers]
  • Note [ClassOp/DFun selection]
  • Note [Single-method classes]
  • Note [Subtle interaction of recursion and overlap]
  • Note [Tricky type variable scoping]
  • Note [Deriving inside TH brackets]
  • Note [Associated type instances]
  • Note [Result kind signature for a data family instance]
  • Note [Eta-reduction for data families]
  • Note [Default methods in the type environment]
  • Note [Typechecking plan for instance declarations]
  • Note [Recursive superclasses]
  • Note [Solving superclass constraints]
  • Note [Silent superclass arguments] (historical interest only)
  • Note [Mismatched class methods and associated type families]
  • Note [Avoid -Winaccessible-code when deriving]
  • Note [Instance method signatures]
  • Note [Export helper functions]
  • Note [Default methods in instances]
  • Note [INLINE and default methods]
  • Note [SPECIALISE instance pragmas]
• compiler/typecheck/TcInteract.hs
  • Note [Basic Simplifier Plan]
  • Note [Unflatten after solving the simple wanteds]
  • Note [Running plugins on unflattened wanteds]
  • Note [The solveSimpleWanteds loop]
  • Note [The Solver Invariant]
  • Note [Replacement vs keeping]
  • Note [Multiple matching irreds]
  • Note [Solving irreducible equalities]
  • Note [Do not add duplicate derived insolubles]
  • Note [Shortcut solving]
  • Solving fully
  • Note [Shortcut solving: type families]
  • Note [Shortcut solving: incoherence]
  • Note [Shortcut try_solve_from_instance]
  • Note [Shadowing of Implicit Parameters]
  • Note [Type inference for type families with injectivity]
  • Note [Cache-caused loops]
  • Note [Efficient Orientation]
  • Note [Carefully solve the right CFunEqCan]
  • Note [Avoid double unifications]
  • Note [Do not unify representational equalities]
  • Note [FunDep and implicit parameter reactions]
  • Note [Weird fundeps]
  • Note [Looking up primitive equalities in quantified constraints]
  • Note [Top-level reductions for type functions]
  • Note [FunEq occurs-check principle]
  • Note [Cached solved FunEqs]
  • Note [MATCHING-SYNONYMS]
  • Note [Improvement orientation]
  • Note [No FunEq improvement for Givens]
  • Note [Reduction for Derived CFunEqCans]
  • Note [Instances in no-evidence implications]
  • Note [Instance and Given overlap]
  • Note [Naturally coherent classes]
  • Note [Local instances and incoherence]
• compiler/typecheck/TcMType.hs
  • Note [ExpType]
  • Note [TcLevel of ExpType]
  • Note [Skolemising type variables]
  • Note [Kind substitution when instantiating]
  • Note [TyVarTv]
  • Note [Name of an instantiated type variable]
  • Note [Unification variables need fresh Names]
  • Note [Level check when unifying]
  • Note [Never need to instantiate coercion variables]
  • Note [Dependent type variables]
  • Note [CandidatesQTvs determinism and order]
  • Note [Naughty quantification candidates]
  • Note [Order of accumulation]
  • Note [Defaulting with -XNoPolyKinds]
  • Note [What is a meta variable?]
  • Note [What is zonking?]
  • Note [Zonking to Skolem]
  • Note [Silly Type Synonyms]
  • Note [zonkCt behaviour]
  • Note [Sharing in zonking]
• compiler/typecheck/TcMatches.hs
  • Note [Polymorphic expected type for tcMatchesFun]
  • Note [Case branches must never infer a non-tau type]
  • Note [Treat rebindable syntax first]
  • Note [ApplicativeDo and constraints]
• compiler/typecheck/TcPat.hs
  • Note [Subsumption check at pattern variables]
  • Note [Nesting]
  • Note [NPlusK patterns]
  • Note [Hopping the LIE in lazy patterns]
  • Note [Matching constructor patterns]
  • Note [Arrows and patterns]
  • Note [Existential check]
• compiler/typecheck/TcPatSyn.hs
  • Note [Pattern synonym error recovery]
  • Note [Remove redundant provided dicts]
  • Note [Equality evidence in pattern synonyms]
  • Note [Coercions that escape]
  • Note [The pattern-synonym signature splitting rule]
  • Note [Checking against a pattern signature]
  • Note [Builder for a bidirectional pattern synonym]
  • Note [Redundant constraints for builder]
  • Note [As-patterns in pattern synonym definitions]
  • Note [Type signatures and the builder expression]
  • Note [Record PatSyn Desugaring]
• compiler/typecheck/TcRnDriver.hs
  • Note [DFun impedance matching]
  • Note [DFun knot-tying]
  • Note [Root-main Id]
  • Note [Initialising the type environment for GHCi]
  • Note [Deferred type errors in GHCi]
  • Note [GHCi Plans]
  • Note [TcRnExprMode]
  • Note [Kind-generalise in tcRnType]
• compiler/typecheck/TcRnExports.hs
  • Note [Exports of data families]
  • Note [Avails of associated data families]
  • Note [Modules without a module header]
• compiler/typecheck/TcRnMonad.hs
  • Note [Default types]
  • Note [Constraints and errors]
  • Note [Masking exceptions in forkM_maybe]
• compiler/typecheck/TcRnTypes.hs
  • Note [Identity versus semantic module]
  • Note [Constraints in static forms]
  • Note [Tracking unused binding and imports]
  • Note [The Global-Env/Local-Env story]
  • Note [Escaping the arrow scope]
  • Note [Meaning of IdBindingInfo]
  • Note [Bindings with closed types: ClosedTypeId]
  • Note [Type variables in the type environment]
  • Note [Complete and partial type signatures]
  • Note [sig_inst_tau may be polymorphic]
  • Note [Wildcards in partial signatures]
  • Note [Hole constraints]
  • Note [CIrredCan constraints]
  • Note [Ct/evidence invariant]
  • Note [Ct kind invariant]
  • Note [Resetting cc_pend_sc]
  • Note [Dropping derived constraints]
  • Note [Custom type errors in constraints]
  • Note [When superclasses help]
  • Note [Given insolubles]
  • Note [Insoluble holes]
  • Note [Needed evidence variables]
  • Note [Shadowing in a constraint]
  • Note [Skolems in an implication]
  • Note [Insoluble constraints]
  • Note [Evidence field of CtEvidence]
  • Note [Bind new Givens immediately]
  • Note [Constraint flavours]
  • Note [eqCanRewrite]
  • Note [Wanteds do not rewrite Wanteds]
  • Note [Deriveds do rewrite Deriveds]
  • Note [funEqCanDischarge]
  • Note [eqCanDischarge]
  • Note [SubGoalDepth]
  • Note [Skolem info for pattern synonyms]
  • Note [SigSkol SkolemInfo]
• compiler/typecheck/TcRules.hs
  • Note [Typechecking rules]
  • Note [TcLevel in type checking rules]
  • Note [The SimplifyRule Plan]
  • Note [Solve order for RULES]
  • Note [RULE quantification over equalities]
  • Note [Quantifying over coercion holes]
  • Note [Simplify cloned constraints]
• compiler/typecheck/TcSMonad.hs
  • Note [WorkList priorities]
  • Note [Prioritise equalities]
  • Note [Prioritise class equalities]
  • Note [Solved dictionaries]
  • Note [Do not add superclasses of solved dictionaries]
  • Note [Example of recursive dictionaries]
  • Note [Detailed InertCans Invariants]
  • Note [EqualCtList invariants]
  • Note [Type family equations]
  • Note [inert_eqs: the inert equalities]
  • Note [Extending the inert equalities]
  • Note [K3: completeness of solving]
  • Note [Flavours with roles]
  • Note [lookupFlattenTyVar]
  • Note [Do not add duplicate quantified instances]
  • Note [kickOutRewritable]
  • Note [Rewrite insolubles]
  • Note [Unsolved Derived equalities]
  • Note [When does an implication have given equalities?]
  • Note [Let-bound skolems]
  • Note [Tuples hiding implicit parameters]
  • Note [Solving CallStack constraints]
  • Note [The TcS monad]
  • Note [Do not inherit the flat cache]
  • Note [Propagate the solved dictionaries]
  • Getters and setters of TcEnv fields
  • Note [Residual implications]
• compiler/typecheck/TcSigs.hs
  • Note [Scoped tyvars]
  • Note [Binding scoped type variables]
  • Note [Fail eagerly on bad signatures]
  • Note [Pattern bindings and complete signatures]
• compiler/typecheck/TcSimplify.hs
  • Note [Fail fast if there are insoluble kind equalities]
  • Note [Fail fast on kind errors]
  • Note [When to do type-class defaulting]
  • Note [Must simplify after defaulting]
  • Note [Top-level Defaulting Plan]
  • Note [Safe Haskell Overlapping Instances]
  • Note [Safe Haskell Overlapping Instances Implementation]
  • Note [No defaulting in the ambiguity check]
  • Note [Superclasses and satisfiability]
  • Note [tcNormalise]
  • Note [Inferring the type of a let-bound variable]
  • Note [Emitting the residual implication in simplifyInfer]
  • Note [Add signature contexts as givens]
  • Note [Deciding quantification]
  • Note [Promote momomorphic tyvars]
  • Note [Quantification and partial signatures]
  • Note [Growing the tau-tvs using constraints]
  • Note [Quantification with errors]
  • Note [Default while Inferring]
  • Note [Minimize by Superclasses]
  • Note [Avoid unnecessary constraint simplification]
  • Note [Delete dead Given evidence bindings]
  • Note [Tracking redundant constraints]
  • Note [Cutting off simpl_loop]
  • Note [ApproximateWC]
  • Note [DefaultTyVar]
  • Note [Promote _and_ default when inferring]
  • Note [Promoting unification variables]
  • Note [Float Equalities out of Implications]
  • Note [Float equalities from under a skolem binding]
  • Note [Which equalities to float]
  • Note [Skolem escape]
  • Note [What prevents a constraint from floating]
  • Note [Avoiding spurious errors]
  • Note [Multi-parameter defaults]
• compiler/typecheck/TcSplice.hs
  • Note [How top-level splices are handled]
  • Note [How brackets and nested splices are handled]
  • Note [Template Haskell state diagram]
  • Note [Template Haskell levels]
  • Note [Running typed splices in the zonker]
  • Note [Exceptions in TH]
  • Note [Concealed TH exceptions]
  • Note [Freshen reified GADT constructors’ universal tyvars]
  • Note [Reifying field labels]
• compiler/typecheck/TcTyClsDecls.hs
  • Note [Grouping of type and class declarations]
  • Note [Check role annotations in a second pass]
  • Note [Kind checking for type and class decls]
  • Note [Skip decls with CUSKs in kcLTyClDecl]
  • Open type families
  • Note [How TcTyCons work]
  • Note [Type environment evolution]
  • Note [Missed opportunity to retain higher-rank kinds]
  • Note [Don’t process associated types in kcLHsQTyVars]
  • Note [Required, Specified, and Inferred for types]
  • Associated types
  • How it works
  • Design alternatives
  • Test cases (and tickets) relevant to these design decisions
  • Note [Inferring kinds for type declarations]
  • Note [Tricky scoping in generaliseTcTyCon]
  • Note [Recursion and promoting data constructors]
  • Note [Kind-checking for GADTs]
  • Note [Type checking recursive type and class declarations]
  • Note [Kind checking recursive type and class declarations]
  • Note [Declarations for wired-in things]
  • Note [Associated type defaults]
  • Note [Type-checking default assoc decls]
  • Note [Instantiating a family tycon]
  • Note [Generalising in tcFamTyPatsGuts]
  • Note [Constraints in patterns]
  • Note [Quantifying over family patterns]
  • Note [Quantified kind variables of a family pattern]
  • Note [Infix GADT constructors]
  • Note [Checking GADT return types]
  • Note [mkGADTVars]
  • Note [Substitution in template variables kinds]
  • Note [Recover from validity error]
  • Note [Class method constraints]
  • Note [Abort when superclass cycle is detected]
  • Note [Default method type signatures must align]
  • Note [Splitting nested sigma types in class type signatures]
  • Note [Checking partial record field]
• compiler/typecheck/TcTyDecls.hs
  • Note [Superclass cycle check]
  • Note [Role inference]
  • Note [Role-checking data constructor arguments]
  • Note [Coercions in role inference]
  • Note [Default roles for abstract TyCons in hs-boot/hsig]
  • Note [Default method Ids and Template Haskell]
  • Note [Polymorphic selectors]
  • Note [Naughty record selectors]
  • Note [GADT record selectors]
  • Note [Selector running example]
• compiler/typecheck/TcType.hs
  • Note [TcTyVars and TyVars in the typechecker]
  • Note [Coercion variables in free variable lists]
  • Note [TcRhoType]
  • Note [Signature skolems]
  • Note [TyVars and TcTyVars during type checking]
  • Note [TcLevel and untouchable type variables]
  • Note [WantedInv]
  • Note [Skolem escape prevention]
  • Note [TcLevel assignment]
  • Note [Silly type synonym]
  • Note [anyRewritableTyVar must be role-aware]
  • Note [Expanding superclasses]
  • Note [Lift equality constaints when quantifying]
  • Note [Quantifying over equality constraints]
  • Note [Inheriting implicit parameters]
  • Note [Quantifying over equality constraints]
  • Note [AppTy and ReprEq]
  • Note [Visible type application]
  • Note [Foreign import dynamic]
  • Note [Marshalling void]
  • Note [Paterson conditions on PredTypes]
• compiler/typecheck/TcTypeNats.hs
  • Note [Type-level literals]
  • Note [Adding built-in type families]
  • Note [Weakened interaction rule for subtraction]
• compiler/typecheck/TcTypeable.hs
  • Note [Grand plan for Typeable]
  • Note [Representing TyCon kinds: KindRep]
• compiler/typecheck/TcUnify.hs
  • Note [Herald for matchExpectedFunTys]
  • Note [matchExpectedFunTys]
  • Note [Subsumption checking: tcSubType]
  • Wrinkle 1: Note [Deep skolemisation]
  • Wrinkle 2: Note [Co/contra-variance of subsumption checking]
  • Wrinkle 3: Note [Higher rank types]
  • Note [Don’t skolemise unnecessarily]
  • Note [Settting the argument context]
  • Note [Deep instantiation of InferResult]
  • Note [Promoting a type]
  • Note [Promotion and higher rank types]
  • Note [When to build an implication]
  • Note [Check for equality before deferring]
  • Note [Care with type applications]
  • Note [Mismatched type lists and application decomposition]
  • Note [Expanding synonyms during unification]
  • Note [Deferred Unification]
  • Note [TyVar/TyVar orientation]
  • Note [Deeper level on the left]
  • Note [Fmv Orientation Invariant]
  • Note [Eliminate flat-skols]
  • Note [Avoid unnecessary swaps]
  • Note [Eliminate younger unification variables]
  • Note [Prevent unification with type families]
  • Note [Refactoring hazard: checkTauTvUpdate]
  • Note [Type synonyms and the occur check]
  • Note [Non-TcTyVars in TcUnify]
  • Note [Unifying untouchables]
  • Note [Occurrence checking: look inside kinds]
  • Note [Checking for foralls]
• compiler/typecheck/TcValidity.hs
  • Note [The ambiguity check for type signatures]
  • Note [When to call checkAmbiguity]
  • Note [Implicit parameters and ambiguity]
  • Note [When we don’t check for ambiguity]
  • Note [Higher rank types]
  • Note [Correctness and performance of type synonym validity checking]
  • Note [Unsaturated type synonyms in GHCi]
  • Note [Type variables escaping through kinds]
  • Note [Liberal type synonyms]
  • Note [Implicit parameters in instance decls]
  • Note [Validity checking for constraints]
  • Note [ConstraintKinds in predicates]
  • Note [Irreducible predicates in superclasses]
  • Note [Simplifiable given constraints]
  • Note [Kind polymorphic type classes]
  • Note [Instances of built-in classes in signature files]
  • Note [Casts during validity checking]
  • Note [Validity checking of HasField instances]
  • Note [Valid ‘deriving’ predicate]
  • Note [Equality class instances]
  • Note [Instances and constraint synonyms]
  • Note [Paterson conditions]
  • Note [Type families in instance contexts]
  • Note [Invisible arguments and termination]
  • Note [Check type-family instance binders]
  • Note [Matching in the consistent-instantation check]
  • Note [Checking consistent instantiation]
  • Note [Printing conflicts with class header]
  • Note [Unused explicitly bound variables in a family pattern]
  • Note [Oversaturated type family equations]
  • Note [Bad TyCon telescopes]
  • Note [Ambiguous kind vars]