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Set

The Set collection in Tish.

Overview

Set is a collection of unique values. It works identically across every Tish backend — the interpreter, the bytecode VM, and native (AOT) compiled binaries. Membership uses SameValueZero equality: NaN is equal to NaN, +0 and -0 are the same value, primitives compare by value, and objects compare by identity. Insertion order is preserved.

let s = new Set([1, 2, 2, 3])   // {1, 2, 3}
s.size                          // 3

Constructor

FormResult
new Set()An empty set.
new Set(iterable)A set seeded from an array (duplicates dropped).

Properties & methods

MemberDescription
.sizeNumber of values (a computed property).
.add(value)Insert value if not already present.
.has(value)true if value is a member.
.delete(value)Remove value; returns true if it was present.
.clear()Remove all values.
.values() / .keys()An iterator over the values in insertion order (identical for a Set).
.entries()An iterator over [value, value] pairs.

Iteration

.values(), .keys(), and .entries() return real iterators (objects with a .next() yielding { value, done }), so they work directly, in for...of, and with spread:

let s = new Set([2, 3, 4])
let total = 0
for (let v of s.values()) {
  total = total + v
}
total              // 9
 
s.values().next()  // { value: 2, done: false }
[...s.values()]    // [2, 3, 4]

Examples

let seen = new Set()
seen.add("a")
seen.add("b")
seen.add("a")        // duplicate — ignored
seen.size            // 2
seen.has("b")        // true
seen.delete("a")     // true
seen.size            // 1
 
// SameValueZero: NaN is a single member.
let n = new Set([NaN, NaN])
n.size               // 1
n.has(NaN)           // true

Compatibility notes (v1)

  • forEach is not available yet, and .add() does not return the set (no method chaining). Iterate with for...of over .values().
  • Direct for (x of set) and [...set] are not wired yet — iterate via .values() / .keys() / .entries(). Those now return iterators, so [...set.values()] and set.values().next() work like JavaScript.
  • console.log(set) prints the underlying object rather than Set(n) {…}. Log [...set.values()] style output for a clean view (set.values()).

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