#summary Definition of a function.
#labels Glossary

= Function =

A function is a named expression that [Consumption consumes] zero or more values from the stack, and [Production produces] zero or more values on to the stack. A function may also have [SideEffect side-effects]. 

A function can be pushed on to a stack by [Quotation quoting it].

== Examples === 

Some example of function definitions are:

{{{
>> define f { 40 2 + }
stack: _empty_
>> define g { 42 eq ["correct answer"] ["wrong answer"] if writeln }
stack: _empty_
>> 12 g
wrong answer
stack: _empty_
>> f g
that is the answer
stack: _empty_
>> [f]
stack: [f]
}}}