SWI-Prolog -- gensym/2

Documentation
- Reference manual
  - The SWI-Prolog library
    - library(gensym): Generate unique symbols
- Packages

Availability::- use_module(library(gensym)).(can be autoloaded)

gensym(+Base, -Unique)

Generate <Base>1, <Base>2, etc atoms on each subsequent call. Note that there is nothing that prevents other parts of the application to‘invent’the same identifier. The predicate gensym/2 is thread-safe in the sense that two threads generating identifiers from the same Base will never generate the same identifier.

See also: uuid/1, term_hash/2, variant_sha1/2 may be used to generate various unique or content-based identifiers safely.