Map

Immutable key-value map operations. All functions return new maps — they never mutate the original.

Functions

Function	Signature	Description
Map.empty	() -> Map<K, V>	Create an empty map
Map.fromArray	Array<(K, V)> -> Map<K, V>	Create a map from key-value pairs
Map.get	Map<K, V>, K -> Option<V>	Look up a value by key
Map.set	Map<K, V>, K, V -> Map<K, V>	Add or update a key-value pair
Map.remove	Map<K, V>, K -> Map<K, V>	Remove a key-value pair
Map.has	Map<K, V>, K -> boolean	Check if a key exists
Map.keys	Map<K, V> -> Array<K>	Get all keys
Map.values	Map<K, V> -> Array<V>	Get all values
Map.entries	Map<K, V> -> Array<(K, V)>	Get all key-value pairs
Map.size	Map<K, V> -> number	Number of entries
Map.isEmpty	Map<K, V> -> boolean	True if map has no entries
Map.merge	Map<K, V>, Map<K, V> -> Map<K, V>	Merge two maps (second wins on conflict)

Examples

// Create a map from key-value pairs
const config = Map.fromArray([("host", "localhost"), ("port", "8080")])

// All operations are immutable
const updated = config
  |> Map.set("port", "3000")
  |> Map.set("debug", "true")

// Safe lookup returns Option
const port = Map.get(config, "port")   // Some("8080")
const missing = Map.get(config, "foo") // None

// Check membership
const hasHost = config |> Map.has("host")   // true

// Convert to arrays
const keys = config |> Map.keys      // ["host", "port"]
const values = config |> Map.values  // ["localhost", "8080"]

// Merge maps (second map's values win on key conflict)
const defaults = Map.fromArray([("port", "80"), ("host", "0.0.0.0")])
const merged = Map.merge(defaults, config)
// Map { "port" => "8080", "host" => "localhost" }