Sets

Sets represent an unordered collection of unique elements. These are implemented using hash tables.

a := |10, 20, 30|
b := |20, 30|
>> a.overlap(b)
= |20|

Syntax

Sets are written using |...| vertical pipes with comma-separated items:

nums := |10, 20, 30|

Empty sets must specify the set type explicitly:

empty : |Int| = ||

For type annotations, a set that holds items with type T is written as |T|.

Comprehensions

Similar to lists, sets can use comprehensions:

set := |10*i for i in 10|
set2 := |10*i for i in 10 if i mod 2 == 0|
set3 := |-10, 10*i for i in 10|

Accessing Items

Sets internally store their items in a list, which you can access with the .items field. This is a constant-time operation that produces an immutable view:

set := |10, 20, 30|
>> set.items
= [10, 20, 30]

Length

Set length can be accessed by the .length field:

>> |10, 20, 30|.length
= 3

Iteration

You can iterate over the items in a table like this:

for item in set
    ...

for i, item in set
    ...

Set iteration operates over the value of the set when the loop began, so modifying the set during iteration is safe and will not result in the loop iterating over any of the new values.

API

API documentation