Map

A Map in Mech is an unordered collection of unique keys, each associated with a corresponding value. Maps are useful for representing associative data, such as key-value pairs, dictionaries, or lookup tables.

Unlike matrices, maps do not require homogeneous values, but keys must be unique within the map.

Syntax

You can define maps using curly braces {} with a colon : to separate keys from values.

Examples:

{}                       -- An empty map
{"a": 1}                 -- A single key-value pair
{"a": 10, "b": 20}       -- Multiple key-value pairs
{"a": {"b": 2}}          -- Nested maps
{
  "a": 10
  "b": 20
  "c": 30
}                        -- Multi-line format

Evaluates to:

{}-- An empty map{"a":1}-- A single key-value pair{"a":10, "b":20}-- Multiple key-value pairs{"a":{"b":2}}-- Nested maps{"a":10, "b":20, "c":30}-- Multi-line format

Notes:

Keys are typically strings but may support additional types in future.
Keys must be unique.
Values can be any Mech kind (number, string, bool, matrix, another map, etc).

Kind

The kind of a map describes the type of its keys and values:

<{string:u8}>-- A map from strings to unsigned 8-bit integers<{string:{string:u8}}>-- A nested map<{T:U}>-- A generic map from kind T to kind U

If either key or value kinds are dynamic, an underscore _ is used:

<{_:_}>-- A fully dynamic map<{string:_}>-- A map with known key kind but unknown value kind

Construction

Maps can be constructed inline or from other data sources (e.g., parsed JSON, CSV headers, or computed results).

m:={"name":"Alice", "age":30}

You can also dynamically insert or build maps using assignment (see Section 5).

Accessing Elements

Elements in a map are accessed using square brackets [] with the key.

m:={"a":10, "b":20}m{"a"}--

Returns 10

If the key does not exist, the result is none.

For nested maps, use multiple brackets:

m := {"a": {"b": 2}}
m{"a"}{"b"}   -- Returns 2

Assigning Elements

Maps can be modified if they are declared mutable with ~.

~m := {}
m{"a"} = 42     -- Adds or updates key "a"
m{"b"} = 17     -- Adds key "b"

You can also assign to nested keys:

~m := {"config": {}}
m{"config"}{"theme"} = "dark"