| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
Data.Function.Poly
- type family TypeListToArity (xs :: [*]) (r :: *) :: * where ...
- type family ArityToTypeList (r :: *) :: [*] where ...
- type family Result (f :: *) :: * where ...
- type family ArityMinusTypeList (r :: *) (xs :: [*]) :: * where ...
- type ArityTypeListIso c l r = (ArityMinusTypeList c l ~ r, c ~ TypeListToArity l r)
- type family InjectLast (x :: *) (f :: *) :: * where ...
- type family Append (xs :: [*]) (x :: *) :: [*] where ...
- type family ExpectArity (xs :: [*]) (f :: *) :: Constraint where ...
- type family ExpectLast (x :: *) (f :: *) :: Constraint where ...
- type family Head (xs :: [k]) :: k where ...
- type family Tail (xs :: [k]) :: [k] where ...
- data HList xs where
- class ExpectArity xs f => ConsumeArity xs f result | xs f -> result where
- type family HasResult (f :: *) (r :: *) :: Constraint where ...
Documentation
type family TypeListToArity (xs :: [*]) (r :: *) :: * where ... Source #
Provide a type-level list of types xs, and a final result type r,
construct a chain of arrows -> / n-ary function (which is right-associative)
of each type in xs, ending in r.
Equations
| TypeListToArity '[] r = r | |
| TypeListToArity (x ': xs) r = x -> TypeListToArity xs r |
type family ArityToTypeList (r :: *) :: [*] where ... Source #
The inverse of TypeListToArity.
Equations
| ArityToTypeList (x -> r) = x ': ArityToTypeList r | |
| ArityToTypeList r = '[] |
type family ArityMinusTypeList (r :: *) (xs :: [*]) :: * where ... Source #
Trim an n-ary function / chain of arrows -> with a type-level list of
types xs, where each element of xs must unify with each element of
the cons-list made with ->.
Equations
| ArityMinusTypeList r '[] = r | |
| ArityMinusTypeList (x -> r) (x ': xs) = ArityMinusTypeList r xs |
type ArityTypeListIso c l r = (ArityMinusTypeList c l ~ r, c ~ TypeListToArity l r) Source #
type family InjectLast (x :: *) (f :: *) :: * where ... Source #
Injects a type to the base of the function arity chain.
Equations
| InjectLast x f = TypeListToArity (Append (ArityToTypeList f) x) (Result f) |
type family ExpectArity (xs :: [*]) (f :: *) :: Constraint where ... Source #
Inductively constrain a function's initial arity to match a type list; as a read-only style of static arity assurance.
Equations
| ExpectArity '[] f = () | |
| ExpectArity (x ': xs) (x -> remainder) = ExpectArity xs remainder |
type family ExpectLast (x :: *) (f :: *) :: Constraint where ... Source #
Expect the last parameter in your stack of arity to have a type.
Equations
| ExpectLast x (x -> remainder) = () | |
| ExpectLast x (y -> remainder) = ExpectLast x remainder |
type family Head (xs :: [k]) :: k where ... Source #
Duplicate of singletons
Head function for kind-polymorphic type-level lists.
Equations
| Head (x ': xs) = x |
class ExpectArity xs f => ConsumeArity xs f result | xs f -> result where Source #
Lift the HList's internal type-level list of types to a constraint context.
Minimal complete definition
Methods
appN :: f -> HList xs -> result Source #
Use a heterogeneously-typed list of values as input to an n-ary function, where types must unify statically.
Instances
| ConsumeArity ([] *) r r Source # | |
| (ConsumeArity xs f r, ExpectArity ((:) * x xs) (x -> f)) => ConsumeArity ((:) * x xs) (x -> f) r Source # | |