A.23 library(listing): List programs and pretty print clauses
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Availability::- use_module(library(listing)).(can be autoloaded)
Sourcelisting
Lists all predicates defined in the calling module. Imported predicates are not listed. To list the content of the module mymodule, use one of the calls below. 
?- mymodule:listing.
?- listing(mymodule:_).