Editing Stack-oriented programming (section)

=== Procedures ===
A procedure in a stack-based programming language is treated as a data object in its own right. In PostScript, procedures are denoted between <code>{</code> and <code>}</code>.

For example, in PostScript syntax,

<code>{ dup mul }</code>

represents an anonymous procedure to duplicate what is on the top of the stack and then multiply the result – a squaring procedure.

Since procedures are treated as simple data objects, names with procedures can be defined. When they are retrieved, they are executed directly.

Dictionaries provide a means of controlling scoping, as well as storing definitions.

Since data objects are stored in the top-most dictionary, an unexpected ability arises naturally: when looking up a definition from a dictionary, the topmost dictionary is checked, then the next, and so on. If a procedure is defined that has the same name as another already defined in a different dictionary, the local one will be called.