The abstract syntax of data is its structure described as a data type (possibly, but not necessarily, an abstract data type), independent of any particular representation or encoding.
To be implemented either for computation or communications, a mapping from the abstract syntax to specific machine representations and encodings must be defined; these may be called the "concrete syntax" (in language implementation) or the "transfer syntax" (in communications).
A compiler's internal representation of a program will typically be specified by an abstract syntax in terms of categories such as "statement", "expression" and "identifier". This is independent of the source syntax (concrete syntax) of the language being compiled (though it will often be very similar). A parse tree is similar to an abstract syntax tree but it will typically also contain features such as parentheses which are syntactically significant but which are implicit in the structure of the abstract syntax tree.
Algebraic data types are particularly well-suited to the implementation of abstract syntax.
Famous quotes containing the word abstract:
“A work of art is an abstract or epitome of the world. It is the result or expression of nature, in miniature. For, although the works of nature are innumerable and all different, the result or the expression of them all is similar and single.”
—Ralph Waldo Emerson (1803–1882)