Function definition skeleton

A function definition tells Scheme the name of a new function and how it works. The skeleton of a function definition is a first draft, essentially translating the contract into Scheme syntax but not specifying how the function does its job. It has the following form:

(define (function-name parameter-name)
   ... parameter-name ... )

You can also write functions with multiple parameters:

(define (function-name parameter-name other-parameter-name)
   ... parameter-name ... other-parameter-name ... )

In either case, the definition consists of several parts, each separated by a space (and anywhere you can put a space, you can also put a new line):

"(define ("
The name of the function
The name by which you want to refer to the parameter (if there are more than one, they must be separated by spaces)
A right parenthesis ), matching the one after define
The body of the function (for now, just put the parameter name(s) again, surrounded by "..." ellipses)
A right parenthesis ), matching the one before define

The first four of these are collectively called the header, and traditionally go on one line, with the body starting on the next line.

Example:

(define (cube number)
   ... number ... )

Note that the function-name and parameter-name can each be whatever you want, as long as each is a sequence of letters (and perhaps some punctuation marks, but no spaces). Typically the function-name is chosen to suggest what the function does, and the parameter-name is chosen to suggest the parameter's type or role.

Last modified: Thu Jun 1 14:37:48 EDT 2000

Stephen Bloch / sbloch@adelphi.edu