📋 Collection Operations

Module: array/* | Operators: 39

Work with lists and arrays including filtering, mapping, and aggregation.

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Operator Reference

array/len

Length · 1 argument · returns number

Array length

Parameter	Type	Description
arr	array	The array

(array/len [1 2 3]) // => 3

array/empty?

Empty? · 1 argument · returns boolean

Check if array is empty

Parameter	Type	Description
arr	array	The array

(array/empty? []) // => true

array/first

First · 1 argument · returns any

Get first element

Parameter	Type	Description
arr	array	The array

(array/first [1 2 3]) // => 1

array/last

Last · 1 argument · returns any

Get last element

Parameter	Type	Description
arr	array	The array

(array/last [1 2 3]) // => 3

array/nth

Nth · 2 arguments · returns any

Get element at index

Parameter	Type	Description
arr	array	The array
index	number	Index (0-based)

(array/nth [1 2 3] 1) // => 2

array/slice

Slice · 2–3 arguments · returns array

Extract subarray

Parameter	Type	Description
arr	array	The array
start	number	Start index
end	number	End index (exclusive)

(array/slice [1 2 3 4] 1 3) // => [2, 3]

array/concat

Concat · 2 or more · returns array

Concatenate arrays

Parameter	Type	Description
...arrs	array[]	Arrays to concatenate

(array/concat [1 2] [3 4]) // => [1, 2, 3, 4]

array/append

Append · 2 arguments · returns array

Add item to end (returns new array)

Parameter	Type	Description
arr	array	The array
item	any	Item to add

(array/append [1 2] 3) // => [1, 2, 3]

array/prepend

Prepend · 2 arguments · returns array

Add item to start (returns new array)

Parameter	Type	Description
arr	array	The array
item	any	Item to add

(array/prepend [2 3] 1) // => [1, 2, 3]

array/insert

Insert · 3 arguments · returns array

Insert item at index (returns new array)

Parameter	Type	Description
arr	array	The array
index	number	Index to insert at
item	any	Item to insert

(array/insert [1 3] 1 2) // => [1, 2, 3]

array/remove

Remove · 2 arguments · returns array

Remove item at index (returns new array)

Parameter	Type	Description
arr	array	The array
index	number	Index to remove

(array/remove [1 2 3] 1) // => [1, 3]

array/removeItem

Remove Item · 2 arguments · returns array

Remove first matching item (returns new array)

Parameter	Type	Description
arr	array	The array
item	any	Item to remove

(array/removeItem [1 2 3 2] 2) // => [1, 3, 2]

array/reverse

Reverse · 1 argument · returns array

Reverse array order (returns new array)

Parameter	Type	Description
arr	array	The array

(array/reverse [1 2 3]) // => [3, 2, 1]

array/sort

Sort · 1–3 arguments · returns array

Sort array (returns new array)

Parameter	Type	Description
arr	array	The array
key	string	Field to sort by (for objects)
dir	string	"asc" or "desc"

(array/sort "@items" "price" "desc")

array/shuffle

Shuffle · 1 argument · returns array

Randomly shuffle array (returns new array)

Parameter	Type	Description
arr	array	The array

(array/shuffle [1 2 3 4 5])

array/unique

Unique · 1 argument · returns array

Remove duplicates (returns new array)

Parameter	Type	Description
arr	array	The array

(array/unique [1 2 2 3 1]) // => [1, 2, 3]

array/flatten

Flatten · 1 argument · returns array

Flatten nested arrays one level

Parameter	Type	Description
arr	array	The array

(array/flatten [[1 2] [3 4]]) // => [1, 2, 3, 4]

array/zip

Zip · 2 arguments · returns array

Pair elements from two arrays

Parameter	Type	Description
arr1	array	First array
arr2	array	Second array

(array/zip [1 2] (a "b")) // => [[1, "a"], [2, "b"]]

array/includes

Includes · 2 arguments · returns boolean

Check if array contains item

Parameter	Type	Description
arr	array	The array
item	any	Item to find

(array/includes [1 2 3] 2) // => true

array/indexOf

Index Of · 2 arguments · returns number

Find index of item (-1 if not found)

Parameter	Type	Description
arr	array	The array
item	any	Item to find

(array/indexOf [1 2 3] 2) // => 1

array/find

Find · 2 arguments · returns any

Find first element matching predicate

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/find "@items" (fn "x" (= "@x.status" "active")))

array/findIndex

Find Index · 2 arguments · returns number

Find index of first element matching predicate (-1 if none)

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/findIndex "@items" (fn "x" (= "@x.status" "active")))

array/filter

Filter · 2 arguments · returns array

Keep elements matching predicate

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/filter "@items" (fn "x" (> "@x.price" 100)))

array/reject

Reject · 2 arguments · returns array

Remove elements matching predicate

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/reject "@items" (fn "x" (= "@x.status" "deleted")))

array/map

Map · 2 arguments · returns array

Transform each element

Parameter	Type	Description
arr	array	The array
fn	lambda	Transform function

(array/map "@items" (fn "x" (* "@x.price" 1.1)))

array/reduce

Reduce · 3 arguments · returns any

Reduce array to single value

Parameter	Type	Description
arr	array	The array
fn	lambda	Reducer function (acc, item) => newAcc
init	any	Initial accumulator value

(array/reduce "@items" (fn (acc "x") (+ "@acc" "@x.price")) 0)

array/every

Every · 2 arguments · returns boolean

Check if all elements match predicate

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/every "@items" (fn "x" (> "@x.price" 0)))

array/some

Some · 2 arguments · returns boolean

Check if any element matches predicate

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/some "@items" (fn "x" (= "@x.status" "active")))

array/count

Count · 1–2 arguments · returns number

Count elements (optionally matching predicate)

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/count "@tasks" (fn "t" (= "@t.status" "done")))

array/sum

Sum · 1–2 arguments · returns number

Sum values (optionally by field)

Parameter	Type	Description
arr	array	The array
key	string	Field to sum

(array/sum "@cart.items" "price")

array/avg

Avg · 1–2 arguments · returns number

Average of values (optionally by field)

Parameter	Type	Description
arr	array	The array
key	string	Field to average

(array/avg "@ratings" "score")

array/min

Min · 1–2 arguments · returns number

Minimum value (optionally by field)

Parameter	Type	Description
arr	array	The array
key	string	Field to compare

(array/min "@products" "price")

array/max

Max · 1–2 arguments · returns number

Maximum value (optionally by field)

Parameter	Type	Description
arr	array	The array
key	string	Field to compare

(array/max "@products" "price")

array/groupBy

Group By · 2 arguments · returns any

Group elements by field value

Parameter	Type	Description
arr	array	The array
key	string	Field to group by

(array/groupBy "@orders" "status")

array/partition

Partition · 2 arguments · returns array

Split array by predicate into [matches, nonMatches]

Parameter	Type	Description
arr	array	The array
pred	lambda	Predicate function

(array/partition "@items" (fn "x" (> "@x.price" 50)))

array/take

Take · 2 arguments · returns array

Take first n elements

Parameter	Type	Description
arr	array	The array
n	number	Number of elements

(array/take "@items" 5)

array/drop

Drop · 2 arguments · returns array

Skip first n elements

Parameter	Type	Description
arr	array	The array
n	number	Number of elements to skip

(array/drop "@items" 5)

array/takeLast

Take Last · 2 arguments · returns array

Take last n elements

Parameter	Type	Description
arr	array	The array
n	number	Number of elements

(array/takeLast "@items" 3)

array/dropLast

Drop Last · 2 arguments · returns array

Skip last n elements

Parameter	Type	Description
arr	array	The array
n	number	Number of elements to skip

(array/dropLast "@items" 2)