Experimental library. Should not be used in production code. Details can be changed without advance notice.

The mutations library provides support for generating random mutations of selected types. The library defines default mutation algorithms for the following basic types:

  • atom

  • integer

  • float

  • compound

  • list

The user can add additional mutation algorithms for these or other types by defining objects or categories providing clauses for the mutation/3 predicate and expanding the entity source files using the mutations_store object as the hook object.

This library is expected to eventually be used to support mutation-based fuzz testing.

By default, loading this library loads a set of default mutation algorithms. These can be overriden by defining alternative mutations and a custom loader file.

API documentation

Open the ../../docs/library_index.html#mutations link in a web browser.


To load all entities in this library, load the loader.lgt file:

| ?- logtalk_load(mutations(loader)).


To test this library predicates, load the tester.lgt file:

| ?- logtalk_load(mutations(tester)).


The mutations category complements the type object and thus its predicates are accessed via this object. For example:

| ?- type::mutation(integer, 123, M).
M = 1293

| type::mutation(integer, 123, M).
M = 5123

| type::mutation(integer, 123, M).
M = -123

| type::mutation(integer, 123, M).
M = 23

When there are multiple mutation algorithms for a given type, the predicate type::mutation/3 choses one of them randomly. We can query the number of mutation algorithms available per type using the mutations_store::counter/2 predicate:

| ?- mutations_store::counter(Type, Count).
Type = atom,
Count = 6 ;
Type = integer,
Count = 7 ;

Loading this library also loads the arbitrary library, which provides get_seed/1 and set_seed/1 predicates that can be used to control the pseudo-random number generator.