std/seq

module seq for Seq<T>

The sequence, set and map operations beyond the core's membership, order and lookup, in the prelude. A receiver module over Seq<T>, with T bound per call; a function that takes any collection writes its receiver, self: Collection<T>, and the functions over sets and maps take theirs as a typed first parameter. A receiver S : Seq<T> comes back at its own type, and F<_> : Seq<_> rebuilt in its own constructor.

• first — The element at position 0, or none over an empty sequence: [3, 1, 2] | first is 3.
• last — The element at the last position, or none over an empty sequence: [3, 1, 2] | last is 2.
• reverse — The elements of self in the opposite order, in its own constructor: [1, 2, 3] | reverse is [3, 2, 1].
• distinct — Each value of self once, at its first position, at the type of self: [1, 2, 1, 3, 2] | distinct is [1, 2, 3].
• zip — Pairs of the elements of self and other at equal positions, as long as the shorter: [1, 2, 3] | zip(["a", "b"]) is [Pair(first = 1, second = "a"), Pair(first = 2, second = "b")].
• enumerate — Each element of self paired with its position, counting from 0: ["a", "b"] | enumerate is [Pair(first = 0, second = "a"), Pair(first = 1, second = "b")].
• any — Whether by holds of some value of self; false over an empty collection: [1, 2, 3] | any(x => x > 2) is true.
• all — Whether by holds of every value of self; true over an empty collection: [] | all(x => x > 2) is true.
• find — The first element of self that by accepts, or none: [1, 2, 3, 4] | find(x => x > 2) is 3.
• position — The position of the first element of self that by accepts, counting from 0, or none: [1, 2, 3, 4] | position(x => x > 2) is 2.
• take_while — The leading values of self that by accepts, up to the first it rejects: [1, 2, 5, 1] | take_while(x => x < 3) is [1, 2].
• drop_while — The values of self after the leading ones by accepts, at the type of self: [1, 2, 5, 1] | drop_while(x => x < 3) is [5, 1].
• window — Every run of n consecutive elements of self, in order: [1, 2, 3, 4] | window(2) is [[1, 2], [2, 3], [3, 4]].
• partition — The values of self redistributed by the key by gives: each value once, at its own type, those of one key in one logical partition.
• is_empty — Whether self has no values: [] | is_empty is true.
• join — Every pair of a value of self and a value of other that by relates, in the order of self, then of other: [1, 2] | join([1, 2, 3], (a, b) => a < b) gives the pairs (1, 2), (1, 3) and (2, 3).
• min_by — The value of self that is least, by the key by gives or by the Ordering by gives two values; the first of equals, or none over an empty collection: ["bb", "a", "ccc"] | min_by(s => size(s)) is "a".
• max_by — The value of self that is greatest, by the key by gives or by the Ordering by gives two values; the first of equals, or none over an empty collection: ["bb", "a", "ccc"] | max_by(s => size(s)) is "ccc".
• to_map — A map from the key of each value of self to its value; two values with one key are an evaluation error: ["bb", "a"] | to_map(s => s, s => size(s)) is Map {"bb": 2, "a": 1}.
• range — The Ints from start up to, not including, end, each step after the one before: range(1, 6) is [1, 2, 3, 4, 5], and range(10, 0, -3) is [10, 7, 4, 1].
• with — The map self with key set to value, added or replaced, at the type of self: Map(["a"], [1]) | with("b", 2) is Map {"a": 1, "b": 2}.
• without — The map self without key, whether or not it held it, at the type of self: Map(["a", "b"], [1, 2]) | without("a") is Map {"b": 2}.
• entries — Each association of the map self as a Pair of its key and its value, in the map's order.
• values — The values of the map self, in the map's order: Map(["b", "a"], [2, 1]) | values is [2, 1].
• intersection — The members of both self and other, at the type of self: {1, 2, 3} | intersection({2, 3, 4}) is {2, 3}.
• difference — The members of self that other does not hold, at the type of self: {1, 2, 3} | difference({2, 3, 4}) is {1}.