How to serialize and deserialize objects in Prolog?

Serialization and deserialization of objects in Prolog can be done by changing data into a format that can be restored later. Serialization in Prolog allows you to convert the objects into a stream of bytes and store the object in a way that can be used to recreate the object. Deserialization is quite the opposite of serialization where you take data structured from a Prolog program and restore it back to an object.

To perform these actions, Prolog offers certain built-in library predicates. Here are steps on how to make use of them:

Step 1: To Serialize in Prolog

The predicate to be used here is the write/1.

This can be demonstrated through an example. Let's say you have a fact likes(john, doughnuts) and you want to serialize this. You'd do the following:

tell('facts.pl'),
write(likes(john, doughnuts)),
write('.'),
told,

tell/1 is used to redirect the output to the file 'facts.pl'.

write/1 is then used to write likes(john, doughnuts) out to the file. Followed by write('.') to complete the Prolog clause.

told/0 is used to finish redirecting output to the file and sends subsequent output to the console instead.

Step 2: To Deserialize in Prolog

The predicate to be used here is the read/1.

This can be demonstrated in the following:

see('facts.pl'), 
read(X), 
seen, 
write(X), 
write(.),

see/1 is used to read from 'facts.pl'.

read/1 is used to read in the first Prolog clause from the file. The clause will be stored in X pending to be used in your program.

seen/0 closes the file 'facts.pl'.

Finally, write/1 is used together with write('.') to print out what was read from the file.

This is the basic way to serialize and deserialize an object in Prolog. But bear in mind Prolog data serialization may not be well suited for larger and more complex projects. However, for smaller projects or simple use cases, it works great and is pretty straight forward.