Prolog: Built-In Predicates

Built-in predicates

Prolog has a large number of built-in predicates. The following is a partial list of predicates which should be present in all implementations.

Input predicates: read, get, get0, see, seen.
Output predicates: write, writeq, tab, nl, put, tell, told.
Control predicates: X ; Y, (X -> Y), (X -> Y ; Z), not X, true, repeat, fail, !, abort.
Database manipulation predicates: assert, asserta, assertz, retract, abolish, clause, save, restore.
Arithmetic predicates: is, +, -, *, /, mod, =:=, =\=, >, <, >=, =<.
Listing and debugging predicates: listing, trace, notrace, spy P, nospy P, nospyall, debug, nodebug, tracing controls.
Tests: atom, atomic, number, integer, float, var, nonvar, ==, \==.