qol_gleam/qol_list
Values
pub fn at(in list: List(a), get index: Int) -> Result(a, Nil)Returns the element in the Nth position in the list, with 0 being the first position.
Error(Nil) is returned if the list is not long enough for the given index
or if the index is less than 0.
⚠️ WARNING ⚠️: It’s best to avoid using this function as it would be commonly misused, resulting in poor code. Try to redesign your code and data structure first, and only use this as a last resource (or if you know what you are doing).
Examples
assert at([1, 2, 3], 1) == Ok(2)
assert at([1, 2, 3], 5) == Error(Nil)
Origin
This function was from the stdlib and was deprecated since v0.37.0 as it was misleading and would be commonly misused, resulting in poor code.
pub fn pop(
in haystack: List(a),
one_that is_desired: fn(a) -> Bool,
) -> Result(#(a, List(a)), Nil)Removes the first element in a given list for which the predicate function
returns True.
Returns Error(Nil) if no such element is found.
Examples
assert pop([1, 2, 3], fn(x) { x > 2 }) == Ok(#(3, [1, 2]))
assert pop([1, 2, 3], fn(x) { x > 4 }) == Error(Nil)
assert pop([], fn(_) { True }) == Error(Nil)
Origin
This function was from the stdlib and was deprecated since v0.54.0 as due to confusion with the name.
pub fn pop_map(
in haystack: List(a),
one_that is_desired: fn(a) -> Result(b, c),
) -> Result(#(b, List(a)), Nil)Removes the first element in a given list for which the given function
returns Ok(new_value), then returns the wrapped new_value as well as
list with the value removed.
Returns Error(Nil) if no such element is found.
Examples
assert pop_map([[], [2], [3]], first) == Ok(#(2, [[], [3]]))
assert pop_map([[], []], first) == Error(Nil)
assert pop_map([], first) == Error(Nil)
Origin
This function was from the stdlib and was deprecated since v0.54.0 as due to confusion with the name.
pub fn rotate(list: List(a), by n: Int) -> List(a)Returns a new list with elements rotated from one end to the other.
Examples
assert rotate([1, 2, 3, 4, 5], by: 2) == [3, 4, 5, 1, 2]
assert rotate([1, 2, 3, 4, 5], by: -2) == [4, 5, 1, 2, 3]
Origin
This function is commonly expected from other programming language.