|#lang sicp||package: sicp|
The programs in the book are written in (a subset of) the programming language Scheme. As the years have passed the programming language Scheme has evolved. The language #lang sicp provides you with a version of R5RS (the fifth revision of Scheme) changed slightly in order for programs in SICP to run as is.
To use the sicp language simply use #lang sicp as the first line of your program. If you need to use Racket libraries, then use #%require. R5RS has no require to avoid breaking programs that use the name require. #%require is therefore used instead.
the-empty-stream : stream?
(cons-stream first-expr rest-expr)
(amb expr ...)