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Collection Builtins

Sloplang's rich standard library for working with lists, sets, and maps.

Aggregation functions reduce a collection to a single value.

let nums = [3, 1, 4, 1, 5, 9, 2, 6]

nums | sum | print
nums | product | print
nums | min | print
nums | max | print
nums | count | print

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`fold` is the general-purpose reducer. It takes an initial value and a function of `(accumulator, element)`.

-- Sum via fold
[1, 2, 3, 4, 5] | fold 0 (acc, x) -> acc + x | print

-- Build a string
[1, 2, 3] | fold "" (acc, x) -> acc + "{x} " | trim | print

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`group_by` groups elements by a key function, returning `[[key, [items]], ...]`. Combine with `map` for powerful aggregations.

let words = ["ant", "bat", "ape", "bee", "cat", "cow"]

words
	| group_by ?[0]
	| map g -> "{g[0]}: {g[1] | join \", \"}"
	| print

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Sets support union (`+`), intersection (`&`), and symmetric difference (`^`).

let a = {1, 2, 3, 4}
let b = {3, 4, 5, 6}

a + b | print
a & b | print
a ^ b | print

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