This document describes CHICKEN’s R5RS support, with a heavy emphasis on syntax and procedures. It is based directly on the Revised^5 Report on the. 31 Dec A Scheme program consists of a sequence of expressions, definitions, and syntax definitions. Expressions are described in chapter. 31 Dec 9. R5Rs. Scheme Revised(5) Report on the Algorithmic Language Scheme — Variables and Procedures. main page. top: R5Rs. Scheme.

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Except for continuations created by the call-with-values procedure, all continuations take exactly one value. The escape procedure that is passed to proc has unlimited extent just like any other procedure in Scheme.

Sign up or log in Sign up using Google. As a result, the application of Chez scheme can make every Racket runs magically fast. d5rs

R5RS: Legacy Scheme

These procedures return integers. The use of block structuring to create local bindings alleviates the risk of namespace collision that can otherwise occur.

In general, the mathematical functions log, arcsine, arccosine, and arctangent are multiply defined. R5RS Scheme provides the predicates input-port? The dynamic extent of a procedure call is the period between when the call is initiated and when it returns. Note that it is an error to take the car of the empty list. For the future, it have potential development like Scope sets.

R5RS doesn’t have libraries so the portable way would be to load it or inline it. If the argument to one of these procedures is inexact, then the result r5ds also be inexact. These procedures return the numerator or denominator of their argument; the result is computed as if the argument was represented as a fraction in lowest terms. This process broke with the earlier R n RS approach of unanimity.

R5RS Index (Guile Reference Manual)

The syntactic keyword of a macro may shadow variable bindings, and local variable bindings may shadow keyword bindings. Returns t if obj is a list, otherwise returns f. Scheme is widely used by a number [37] of schools; in particular, a number of introductory Computer Science courses use R55rs in conjunction with the textbook Structure and Interpretation of Computer Programs SICP. If a literal identifier is inserted as a bound identifier then it is in effect renamed to prevent inadvertent captures of free identifiers.


Strings are sequences of characters. Quasiquote forms may be nested. This convention is supported so that arbitrary Scheme programs may be represented as lists.

Scheme (programming language)

A predicate is a procedure that always returns a boolean value t or f. The dynamic order in which proc is applied to the elements of the lists is unspecified.

Thus the value of eqv? Such definitions are known as internal definitions as opposed to the top level definitions described above. If min or max is used to compare numbers of mixed exactness, and the numerical value of the result cannot be represented as an inexact number without loss of accuracy, then the procedure may report a violation of an implementation restriction. There is no simple relationship between a number’s type and its representation inside a computer. R5sr for embedding Scheme code in programs written in other languages is also common, as the relative simplicity of Scheme implementations makes it a popular choice for adding r5rss capabilities to larger systems developed in languages such as C.

Vectors are heterogenous structures whose elements are indexed by integers. Note that it is an error to take the cdr of the empty list. Implementations of Scheme are not required to implement the whole tower of subtypes given under ” Numerical types “, but they must implement a coherent subset consistent with both the purposes of the implementation and the spirit of the Scheme language.

This assumes that neither obj[1] nor obj[2] is an “uninterned symbol” as alluded to in the section on symbols. This identifier is called the syntactic keyword, or simply keyword, of the macro. The phrase “a true value” or sometimes just “true” means any object treated as true by the conditional expressions, and the phrase “a false value” or “false” means any object treated as false by the conditional expressions. The operator and operand expressions are evaluated in an unspecified order and the resulting procedure is passed the resulting arguments.


If an inexact argument has no reasonably close exact equivalent, then a violation of an implementation restriction may be reported.

John Reynolds [24] described a simpler but equally powerful construct in This is assured by special naming and scoping rules for macro expansion and avoids common programming errors that can occur in the macro systems of other programming languages. If the symbol was part of an object returned as the value of a literal expression see ” literal expressions ” or by a call to the read procedure, and its name contains alphabetic characters, then the string returned will contain characters in the implementation’s preferred standard case — some implementations will prefer upper case, others lower case.

It is an error to apply mutation procedures like string-set! Programs are typically stored in files or entered interactively to a running Scheme system, although other paradigms are possible; questions of user interface lie outside the scope of this report.

Another example is Pvtswhich offers a set of visual tools for supporting the learning of Scheme. The reliance on lists as data structures is shared by all Lisp dialects.