Idris2Doc : Data.SnocList.Elem

Data.SnocList.Elem

data Elem : a -> SnocList a -> Type

  A proof that some element is found in a list.

Totality: total
Constructors:

Here : Elem x (sx :< x)

  A proof that the element is at the head of the list

There : Elem x sx -> Elem x (sx :< y)

  A proof that the element is in the tail of the list

dropElem : (sx : SnocList a) -> Elem x sx -> SnocList a

  Remove the element at the given position.

elemMap : (0 f : (a -> b)) -> Elem x sx -> Elem (f x) (map f sx)

  Lift the membership proof to a mapped list

elemToNat : Elem x sx -> Nat

  Erase the indices, returning the numeric position of the element

indexElem : Nat -> (sx : SnocList a) -> Maybe (DPair a (\x => Elem x sx))

  Find the element with a proof at a given position (in reverse), if it is valid

neitherHereNorThere : Not (x = y) -> Not (Elem x sx) -> Not (Elem x (sx :< y))

  An item not in the head and not in the tail is not in the list at all.