ranger
Functions
pub fn create(
validate validate: fn(a) -> Bool,
negate_step negate_step: fn(b) -> b,
add add: fn(a, b) -> a,
compare compare: fn(a, a) -> Order,
) -> fn(a, a, b) -> Result(Iterator(a), Nil)returns a function that can be used to create a range
Examples
> let range =
> create(
> validate: fn(a) { string.length(a) == 1 },
> negate_step: fn(s) { -1 * s },
> add: fn(a: String, b: Int) {
> let assert [code] = string.to_utf_codepoints(a)
> let int_code = string.utf_codepoint_to_int(code)
> let new_int_code = int_code + b
> let assert Ok(new_code) = string.utf_codepoint(new_int_code)
> string.from_utf_codepoints([new_code])
> },
> compare: string.compare,
> )
> range("ab", "e", 1)
Error(Nil)
> let assert Ok(a_to_e) = range("a", "e", 1)
> a_to_e |> iterator.to_list
["a", "b", "c", "d", "e"]
> let assert Ok(z_to_p) = range("z", "p", 1)
> z_to_p |> iterator.to_list
["z", "y", "x", "w", "v", "u", "t", "s", "r", "q", "p"]
> let assert Ok(z_to_p) = range("z", "p", -2)
> z_to_p |> iterator.to_list
["z", "x", "v", "t", "r", "p"]
> let assert Ok(z_to_p) = range("z", "p", 3)
> z_to_p |> iterator.to_list
["z", "w", "t", "q"]
> let range =
> create(
> validate: fn(_) { True },
> negate_step: fn(s) { -1.0 *. s },
> add: fn(a, b) { a +. b },
> compare: float.compare,
> )
> let assert Ok(weird_step_case) = range(1.25, 4.5, -0.5)
> weird_step_case |> iterator.to_list
[1.25, 1.75, 2.25, 2.75, 3.25, 3.75, 4.25]
> let assert Ok(single_item_case) = range(1.25, 1.25, -0.25)
> single_item_case |> iterator.to_list
[1.25]
> let assert Ok(zero_step_case) = range(2.5, 5.0, 0)
> zero_step_case |> iterator.to_list
[2.5]
pub fn create_infinite(
validate validate: fn(a) -> Bool,
add add: fn(a, b) -> a,
compare compare: fn(a, a) -> Order,
) -> fn(a, b) -> Result(Iterator(a), Nil)returns a function that can be used to create an infinite range
should be used carefully because careless use of infinite iterators could crash your app
Examples
> let range =
> create_infinite(
> validate: fn(a) { string.length(a) == 1 },
> add: fn(a: String, b: Int) {
> let assert [code] = string.to_utf_codepoints(a)
> let int_code = string.utf_codepoint_to_int(code)
> let new_int_code = int_code + b
> let assert Ok(new_code) = string.utf_codepoint(new_int_code)
> string.from_utf_codepoints([new_code])
> },
> compare: string.compare,
> )
> let assert Ok(from_a) = range("a", 1)
> from_a |> iterator.take(26) |> iterator.to_list
["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n",
"o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]