SWI-Prolog -- setof/3

Documentation
- Reference manual
  - Built-in Predicates
    - Finding all Solutions to a Goal
      - findall/3
      - findall/4
      - findnsols/4
      - findnsols/5
      - bagof/3
      - setof/3
- Packages

Availability:built-in

Source

[ISO]setof(+Template, +Goal, -Set)

Equivalent to bagof/3, but sorts the result using sort/2 to get a sorted list of alternatives without duplicates.