A symbol in computer programming is a primitive data type whose instances have a human-readable form.
The following programming languages provide runtime support for symbols: Symbols in Julia are interned strings used to represent identifiers in parsed Julia code(ASTs) and as names or labels to identify entities (for example as keys in a dictionary).
In Common Lisp, symbols have the following attributes: a name, a value, a function, a list of properties and a package.
Symbols can be used as identifiers for any kind of named programming constructs: variables, functions, macros, classes, types, goto tags and more.
Symbols, which are not interned in a package, can also be created and have a notation: In PostScript, references to name objects can be either literal or executable, influencing the behaviour of the interpreter when encountering them.
When names are constructed from strings by means of the cvn operator, the set of allowed characters is unrestricted.
In Prolog, symbols (or atoms) are the main primitive data types, similar to numbers.
Contrary to many other languages, it is possible to give symbols a meaning by creating some Prolog facts and/or rules.
These three sentences use symbols (father, zeus, hermes, perseus and sibling) and some abstract variables (X, Y and Z).