/usr/local/lib/swipl/library/occurs.pl
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  • swipl
    • library
      • error.pl
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      • apply.pl
      • lists.pl
      • broadcast.pl
      • predicate_options.pl
      • shlib.pl
      • option.pl
      • thread_pool.pl -- Resource bounded thread management
      • gensym.pl
      • settings.pl
      • arithmetic.pl
      • main.pl
      • readutil.pl
      • operators.pl -- Manage operators
      • pairs.pl -- Operations on key-value lists
      • prolog_source.pl -- Examine Prolog source-files
      • record.pl -- Access compound arguments by name
      • quasi_quotations.pl -- Define Quasi Quotation syntax
      • pure_input.pl -- Pure Input from files and streams
      • solution_sequences.pl -- Modify solution sequences
      • ordsets.pl -- Ordered set manipulation
      • random.pl -- Random numbers
      • base64.pl -- Base64 encoding and decoding
      • aggregate.pl -- Aggregation operators on backtrackable predicates
      • yall.pl -- Lambda expressions
      • sandbox.pl -- Sandboxed Prolog code
      • apply_macros.pl -- Goal expansion rules to avoid meta-calling
      • assoc.pl -- Binary associations
      • prolog_format.pl -- Analyse format specifications
      • csv.pl -- Process CSV (Comma-Separated Values) data
      • pprint.pl -- Pretty Print Prolog terms
      • atom.pl -- Operations on atoms
      • modules.pl -- Module utility predicates
      • occurs.pl -- Finding and counting sub-terms
        • contains_term/2
        • contains_var/2
        • free_of_term/2
        • free_of_var/2
        • occurrences_of_term/3
        • occurrences_of_var/3
        • sub_term/2
        • sub_var/2
        • sub_term_shared_variables/3
      • prolog_xref.pl -- Prolog cross-referencer data collection
      • prolog_colour.pl
      • lazy_lists.pl -- Lazy list handling
      • ugraphs.pl -- Graph manipulation library
      • iostream.pl -- Utilities to deal with streams
      • url.pl -- Analysing and constructing URL
      • www_browser.pl -- Open a URL in the users browser
      • prolog_pack.pl -- A package manager for Prolog
      • git.pl -- Run GIT commands
      • rbtrees.pl -- Red black trees
      • dif.pl -- The dif/2 constraint
      • charsio.pl -- I/O on Lists of Character Codes
      • prolog_stack.pl -- Examine the Prolog stack
      • edinburgh.pl -- Some traditional Edinburgh predicates
      • prolog_clause.pl -- Get detailed source-information about a clause
      • prolog_breakpoints.pl -- Manage Prolog break-points
      • wfs.pl -- Well Founded Semantics interface
      • dialect.pl -- Support multiple Prolog dialects
      • prolog_code.pl -- Utilities for reasoning about code
      • sort.pl
      • dicts.pl -- Dict utilities
      • varnumbers.pl -- Utilities for numbered terms
      • check.pl -- Consistency checking
      • base32.pl -- Base32 encoding and decoding
      • codesio.pl -- I/O on Lists of Character Codes
      • coinduction.pl -- Co-Logic Programming
      • date.pl -- Process dates and times
      • heaps.pl -- heaps/priority queues
      • statistics.pl -- Get information about resource usage
      • terms.pl -- Term manipulation
      • when.pl -- Conditional coroutining
      • backcomp.pl -- Backward compatibility
      • prolog_debug.pl -- User level debugging tools
      • system.pl -- System utilities
      • quintus.pl -- Quintus compatibility
      • ansi_term.pl -- Print decorated text to ANSI consoles
      • utf8.pl -- UTF-8 encoding/decoding on lists of character codes.
      • prolog_config.pl -- Provide configuration information
      • prolog_versions.pl -- Demand specific (Prolog) versions
      • listing.pl -- List programs and pretty print clauses
      • thread.pl -- High level thread primitives
      • ctypes.pl -- Character code classification
      • prolog_profile.pl -- Execution profiler
      • writef.pl -- Old-style formatted write
      • shell.pl -- Elementary shell commands
      • prolog_jiti.pl -- Just In Time Indexing (JITI) utilities
 occurrences_of_term(@SubTerm, @Term, ?Count) is det
Count the number of SubTerms in Term that unify with SubTerm. As this predicate is implemented using backtracking, SubTerm and Term are not further instantiated. Possible constraints are enforced. For example, we can count the integers in Term using
?- freeze(S, integer(S)), occurrences_of_term(S, f(1,2,a), C).
C = 2,
freeze(S, integer(S)).
See also
- occurrences_of_var/3 for an equality (==/2) based variant.