lyng/docs/ImmutableMap.md

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# ImmutableMap built-in class
`ImmutableMap` is an immutable map of key-value pairs.
It implements [Collection] and [Iterable] of [MapEntry].
## Creating
val a = ImmutableMap("a" => 1, "b" => 2)
val b = Map("a" => 1, "b" => 2).toImmutable()
val c = ["a" => 1, "b" => 2].toImmutableMap
>>> void
## Converting
val i = ImmutableMap("a" => 1)
val m = i.toMutable()
m["a"] = 2
assertEquals( 1, i["a"] )
assertEquals( 2, m["a"] )
>>> void
## Members
| name | meaning |
|-----------------|------------------------------------------|
| `size` | number of entries |
| `[key]` | get value by key, or `null` if absent |
| `getOrNull(key)`| same as `[key]` |
| `keys` | list of keys |
| `values` | list of values |
| `+` | merge (rightmost wins), returns new immutable map |
| `toMutable()` | create mutable copy |
[Collection]: Collection.md
[Iterable]: Iterable.md
[MapEntry]: Map.md