Arrays

Load the array stdlib when your expressions need collection work: counting, searching, projection, deduping, and simple aggregation.

import { arrays } from 'bonsai-js/stdlib'
expr.use(arrays)

Basic transforms

Transform	Example	Result
count	selectedRegions |> count	3
first	planTiers |> first	"starter"
last	releaseStages |> last	"production"
reverse	approvalSteps |> reverse	["legal", "finance", "ops"]
flatten	tagGroups |> flatten	["billing", "finance", "ops"]
unique	regions |> unique	["gb", "us", "de"]
join(sep)	invoiceIds |> join(", ")	"INV-1, INV-2"
sort	priorityScores |> sort	[1, 2, 3]

sort sorts numbers numerically and falls back to string comparison for other values.

Higher-order transforms

These accept lambda predicates as arguments for filtering, mapping, and searching.

Transform	Example	Result
filter(pred)	users |> filter(.age >= 18)	Array of matching items
map(fn)	users |> map(.name)	Array of extracted values
find(pred)	users |> find(.age >= 18)	First matching item
some(pred)	users |> some(.age >= 18)	true if any match
every(pred)	users |> every(.age >= 18)	true if all match

Practical examples:

users |> filter(.age >= 18) |> map(.name)
// get names of adult users
// ["Alice", "Charlie"]

orders |> some(.total > 100)
// check if any order exceeds $100
// true

products |> map(.category) |> unique |> sort
// deduplicate and sort categories
// ["electronics", "food", "toys"]

Most array errors are type mismatches: these transforms expect arrays. If the input might be nullable or mixed, normalize it before you reach the expression or guard it with your own custom transform.