What Does R7RS Change Programming in Scheme?

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What Does R7RS

Change Programming in Scheme?

Kazuhiro Hishinuma (Twitter: @kazh98)

Department of Computer Science, Meiji University1-1-1 Higashimita, Tama-ku, Kawasaki-shi, Kanagawa, 214-8571 Japan

K. Hishinuma What Does R7RS Change Programming in Scheme?

.. What is the Schemers’ Soul?

Snap out of it, Schemers!

Scheme is the simplest,the smallest, andthe most powerful language!


.. What is the Programmers’ Utopia?

And..., join us,all lispers and programmers!

Now, the most ideal languageis going to be born!


.. Congratulation!

R7RS-small draftratified by Steering Committee!! 1

1http://lists.scheme-reports.org/pipermail/

scheme-reports/2013-November/003832.htmlK. Hishinuma What Does R7RS Change Programming in Scheme?

http://lists.scheme-reports.org/pipermail/scheme-reports/2013-November/003832.html


.. R7RS says ...

“Scheme demonstrates that

a very small number of rules

for forming expressions, with no restrictions

on how they are composed.”


.. R7RS says ...



for forming expressions,

with no restrictions



.. R7RS says ...



for forming expressions, with no restrictions



.. So, today.

Let us think what isThe Genuine ProgrammingIn R7RS Scheme.


.. Three Hot Changes1

Record-type (cf. pp.27–)

Library System (cf. pp.28–)

Exceptions (cf. pp.54–)

1from R5RSK. Hishinuma What Does R7RS Change Programming in Scheme?

.. Record-type

� �(define-record-type name(cname f1 f2 ...)pred?(f1 ref-f1 set-f1!)(f2 ref-f2 set-f2!)...)� �name Name of the record to be defined

pred? Name of the predicatior for this record

f1, f2, ... Names of the fields of this record


.. e.g. CONS, CAR, CDR

Existing method:� �(define (cons a b)(lambda (s) (s a b)))

(define (car c)(c (lambda (a b) a)))

(define (cdr c)(c (lambda (a b) b)))

� �(define c (cons ’a ’b))

(car c) ;=> ’a

(cdr c) ;=> ’b

(pair? c) ;=> ?!

(set-car! c ’d)

(car c) ;=> ?!


.. e.g. CONS, CAR, CDR

Proposed method:� �(define-record-type <pair>(cons a b)pair?(a car set-car!)(b cdr set-cdr!))� �

(define c (cons ’a ’b))

(car c) ;=> ’a

(cdr c) ;=> ’b

(pair? c) ;=> #t

(set-car! c ’d)

(car c) ;=> ’d


.. define-record-type give Scheme ...

The seed ofObject-Oriented Programming!






1from R5RSK. Hishinuma What Does R7RS Change Programming in Scheme?

.. Good news!

Notation for library systemis standardized!!


.. How to load SRFI-1

Gauche (use srfi-1)

Guile (srfi srfi-1)

Racket (require srfi/1)

R7RS (import (srfi 1))


.. How to make a library

� �(define-library (name ...)(export ep ...)(import (scheme base) ...)(begin(define (p1 args ...)...) ...))

� �name Name of the library

ep ... List of names to be exported


.. What’s this?

SRFI-34 is includedin R7RS!


.. with-exception-handler

e.g.� �(with-exception-handler(lambda (e) Handler for Exception e)(lambda () Procedure which may raise exception))� ��

(error ”This is an error message.”)� �


.. Other Changes

Case sensitivity is now the default in

symbols and character names.

Case-lambda (cf. pp.21–)

The call-with-current-continuation

procedure now has the synonym call/cc.


Think in Scheme,write in Scheme,and show your Scheme!

Thanks for your listening.


.. References

[1] J. Cowan: R7RS-small draft ratified by Steering Committee.The public mailing lists on lists.scheme-reports.org, 2013.http://lists.scheme-reports.org/pipermail/

scheme-reports/2013-November/003832.html

[2] A. Shinn, J. Cowan, and A. Gleckler: Revised7 Report on theAlgorithmic Language Scheme. Steering Committee, SchemeWorking Groups, 2013. http://trac.sacrideo.us/wg/

[3] Y. Kurosaki, and K. Hishinuma: Meiji Scheme Shell improved byMOL. Meiji Scheme Project, Mathematical OptimizationLaboratory, Meiji University. https://github.com/meshmol/mesh

[4] K. Sasagawa: Normal Scheme. Scheme, 2013.http://homepage1.nifty.com/~skz/Scheme/normal.html


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http://trac.sacrideo.us/wg/

https://github.com/meshmol/mesh

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