Declaring and Accessing Maps

Declaring a typed map looks like the table constructors you've always written: the annotation just pins down the key and value types:

local stock: {[string]: number} = {apples = 12, bananas = 5}

Reading and writing use the indexing you know. For keys that are valid identifiers, stock.apples and stock["apples"] reach the same entry; bracket form also handles keys with spaces or ones stored in variables:

stock["cherries"] = 20   -- add a new entry
stock.bananas = 8        -- update an existing one
print(stock["apples"])  -- 12
print(stock["plums"])   -- nil: never set

The type checker watches every write: stock["apples"] = "many" is flagged because "many" isn't a number, and using a number as a key is flagged because keys must be strings.

To delete an entry, assign nil to its key: stock["bananas"] = nil removes it entirely, and later reads give nil. There's no separate delete function; this is the standard Lua idiom, and it still type-checks on a map.