listing/[0,1]

Synopsis

listing

listing(+PredSpecs)

Prints the clauses of all the dynamic procedures currently in the Prolog database, or of PredSpecs, to the current output stream, using portray_clause/1.

Arguments

PredSpecs gen_pred_spec_tree_var [MOD]

a predicate specification, or a list of predicate specifications or atoms

Description

If Predicate is an atom, then listing/1 lists the dynamic procedures for all predicates of that name, as for listing/0

If PredSpecs is a predicate specification of the form Name/Arity, only the clauses for the specified predicate are listed.

PredSpecs can be a list of predicate specifications and/or atoms; for example,

     | ?- listing([concatenate/3, reverse, go/0]).
     

Examples

You could list the entire program to a file using the command

     | ?- tell(file), listing, told.
     

Note that listing/[0,1] does not work on compiled procedures.

listing/1 is dependent on the source module. As a special case,

     | ?- listing(mod:_).
     

will list all the dynamic predicates in module mod. However, listing/0 is not dependent on the source module; it refers instead to the type-in module.

Variables may be included in predicate specifications given to listing/1. For example, you can list clauses for f in any current module with:

     | ?- listing(_:f).
     

Comments

Under the Emacs interface, there is a facility for finding the source code definition for a specified compiled or dynamic procedure and reading it into an edit buffer. This is likely to be more helpful than listing/1 in most cases. See ema-emi-key for more information.