dataprep - v0.7.0

dataprep/non_empty_list

Types

NonEmptyList

opaque </>

NonEmptyList guarantees at least one element. Used by Invalid to ensure every failure carries at least one error.

The type is opaque: callers construct values via single / cons / from_list and observe values via head / tail / to_list / fold / length / reverse. Hiding the constructor lets the internal representation evolve without a breaking release.

pub opaque type NonEmptyList(a)

Values

append

</> 
pub fn append(
  left left: NonEmptyList(a),
  right right: NonEmptyList(a),
) -> NonEmptyList(a)

Concatenate two NonEmptyLists.

concat

</> 
pub fn concat(
  lists: NonEmptyList(NonEmptyList(a)),
) -> NonEmptyList(a)

Flatten a NonEmptyList of NonEmptyLists into a single NonEmptyList.

cons

</> 
pub fn cons(
  head head: a,
  tail tail: NonEmptyList(a),
) -> NonEmptyList(a)

Prepend an element to a NonEmptyList.

flat_map

</> 
pub fn flat_map(
  nel: NonEmptyList(a),
  f: fn(a) -> NonEmptyList(b),
) -> NonEmptyList(b)

Map then flatten.

fold

</> 
pub fn fold(
  nel: NonEmptyList(a),
  from initial: b,
  with f: fn(b, a) -> b,
) -> b

Fold over every item from an initial accumulator.

from_list

</> 
pub fn from_list(l: List(a)) -> Result(NonEmptyList(a), Nil)

Try to create a NonEmptyList from a List. Returns Error(Nil) if the list is empty.

</> 
pub fn head(nel: NonEmptyList(a)) -> a

Return the first element. Total: a NonEmptyList always has one.

length

</> 
pub fn length(nel: NonEmptyList(a)) -> Int

Return the number of elements. Always >= 1.

map

</> 
pub fn map(
  nel: NonEmptyList(a),
  f: fn(a) -> b,
) -> NonEmptyList(b)

Transform every element.

reverse

</> 
pub fn reverse(nel: NonEmptyList(a)) -> NonEmptyList(a)

Reverse the order of elements. The result is itself a NonEmptyList.

single

</> 
pub fn single(value: a) -> NonEmptyList(a)

Create a NonEmptyList with a single element.

tail

</> 
pub fn tail(nel: NonEmptyList(a)) -> List(a)

Return everything after the first element as a plain List. May be empty when the NonEmptyList holds a single element.

to_list

</> 
pub fn to_list(nel: NonEmptyList(a)) -> List(a)

Convert to a plain List.

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