Tzopilotl by Example

15. Sets

15.1 Set Literals

-- Create a set with Set(elements...)
let s = Set(1, 2, 3, 4, 5);

-- Set type annotation: Set<T>
let names Set<String> = Set("Alice", "Bob");

15.2 Membership and Modification

let s = Set(1, 2, 3);

-- contains
s contains(2) println;          -- true
s contains(5) println;          -- false

-- add returns a NEW set; the input is unchanged
let s2 = s add(4);
s2 println;                      -- Set(1, 2, 3, 4)

-- remove returns a new set without the element
let s3 = s remove(2);
s3 println;                      -- Set(1, 3)

-- insert! mutates the set in place (returns the same set for chaining)
var t = Set(1, 2);
t insert!(3);
t insert!(2);                    -- duplicate; no-op
t length println;                -- 3

-- pop! mutates and returns one arbitrary element
let e = t pop!;
t contains(e) println;           -- false (e was just removed)

-- copy: sets are passed by reference; copy when an alias must be independent
var u = t copy;
t insert!(99);
u contains(99) println;         -- false

15.3 Set Operations

let a = Set(1, 2, 3, 4);
let b = Set(3, 4, 5, 6);

union(a, b) println;             -- Set(1, 2, 3, 4, 5, 6)
intersection(a, b) println;      -- Set(3, 4)
difference(a, b) println;        -- Set(1, 2)

15.4 Conversion and Size

let s = Set(3, 1, 2);

s length println;                -- 3
s toArray println;               -- [3, 1, 2]