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►2 SICP Language
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2.1 Introduction
2.2 Built-In
nil
inc
dec
the-empty-stream
cons-stream
stream-null?
runtime
random
amb
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2 SICP Language🔗ℹ

 #lang sicp package: sicp

2.1 Introduction🔗ℹ

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.

2.2 Built-In🔗ℹ

value

nil : null?

An alias for '().

procedure

(inc x) → number?

  x : number?
Returns (+ x 1).

procedure

(dec x) → number?

  x : number?
Returns (- x 1).

value

the-empty-stream : stream?

The null/empty stream.

syntax

(cons-stream first-expr rest-expr)

Produces a stream

procedure

(stream-null? s) → boolean?

  s : stream?
Returns #t if s is the-empty-stream, #f otherwise.

procedure

(runtime) → natural-number/c

Returns the current time measured as the number of microseconds passed since a fixed beginning.

procedure

(random n) → real?

  n : positive?
Returns an random integer between 0 and n-1 (inclusive) if n is an exact integer, otherwise returns a random inexact number between 0 and n (exclusive).

syntax

(amb expr ...)

The amb operator.

Additionally, true, false, identity, and error are provided from Racket.

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