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![]() | Pack logtalk -- logtalk-3.81.0/manuals/_sources/libraries/mutations.rst.txt |
.. _library_mutations:
mutations
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.
Open the `../../docs/library_index.html#mutations <../../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
yes
| type::mutation(integer, 123, M)
.
M = 5123
yes
| type::mutation(integer, 123, M)
.
M = -123
yes
| type::mutation(integer, 123, M)
.
M = 23
yes
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.