Typed tables

A table associates keys with values. Write its type as {[K]: V} or Table<K, V>, where K is the key type and V is the value type:

local scores: {[String]: Int} = {
    ada = 10,
    grace = 20,
}

In the implemented literal form, a field name such as ada becomes a string key when the expected table type uses String keys. As with arrays and record aggregates, the literal needs an expected type.

Typed table allocation and storage are implemented in the compiler and native runtime, but the general source-level table API is intentionally small in 0.1.0-rc.2. Indexing, insertion, removal, iteration, and key inspection are not exposed as complete Pop operations. Table equality is not defined either.

For data with a known set of named fields, use a record. For a fixed ordered collection, use an array. Treat tables in this release as an implemented foundation whose general-purpose collection interface is not finished yet; do not design a program around APIs that are only planned.