SWI-Prolog -- term

Documentation
- Reference manual
  - Built-in Predicates
    - Database
      - Indexing databases
        
        term_hash/2
        
        term_hash/4
        
        variant_sha1/2
        
        variant_hash/2
- Packages

Availability:built-in

[det]term_hash(+Term, +Depth, +Range, -HashKey)

As term_hash/2, but only considers Term to the specified Depth. The top-level term has depth 1, its arguments have depth 2, etc. That is, Depth = 0 hashes nothing; Depth = 1 hashes atomic values or the functor and arity of a compound term, not its arguments; Depth = 2 also indexes the immediate arguments, etc.

HashKey is in the range [0 ...Range-1]. Range must be in the range [1 ... 2147483647].