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Source for ticket #218

cc

changetime

2011-09-11 07:52:01

component

WG1 - Reader Syntax

description

The current BNF for symbol syntax is rather
cumbersome, having to account for the fact
that +inf.0, -inf.0 and +nan.0 are numbers
even though they do not begin with a numeric
prefix.

A simple solution would be to use an alternative
such as 0/1, 0/-1 and 0/0, respectively.  These
are shorter, more self explanatory, and do not
conflict with the definition of symbol syntax.

id

keywords

milestone

owner

alexshinn

priority

major

reporter

alexshinn

resolution

wontfix

severity

status

closed

summary

infinity/nan syntax

time

2011-06-07 21:10:16

type

defect

Changes

Change at time 2011-09-11 07:52:01

author

cowan

field

comment

newvalue

WG1 rejected this proposal.

oldvalue

raw-time

1315702321000000

ticket

time

2011-09-11 07:52:01

Change at time 2011-09-11 07:52:01

author

cowan

field

resolution

newvalue

wontfix

oldvalue

raw-time

1315702321000000

ticket

time

2011-09-11 07:52:01

Change at time 2011-09-11 07:52:01

author

cowan

field

status

newvalue

closed

oldvalue

new

raw-time

1315702321000000

ticket

time

2011-09-11 07:52:01

Change at time 2011-06-08 03:44:36

author

cowan

field

comment

newvalue

Standardization is not about inventing new stuff unless we have to.  Currently:

 * Racket, Gauche, Gambit, Chicken (with some bugs), Guile, Kawa, Chibi, Chez, SCM, Ikarus, Larceny, !IronScheme, Ypsilon, Mosh, STklos support the `+inf.0`, `-inf.0`, `+nan.0` syntaxes.
 * Bigloo prints `+Infinity`, `-Infinity`, `Infinity` on output but treats these as symbols on input.
 * Scheme48 prints `#{Inf}`, `#{-Inf}`, `#{NaN}` but does not accept these syntaxes on input.
 * SISC prints `infinity.0`, `-infinity.0`, `nan.0` but treats these as symbols on input.
 * !SigScheme doesn't do flonums.
 * MIT Scheme, scsh report errors and so needs no such syntax.
 * Scheme 9 reports errors for the infinities and evaluates `(/ 0.0 0.0)` to `0.0`.

In addition, those syntaxes look exact, not inexact.  You could fix that with a decimal point, but people would tend to forget where it went (is it 0./1, 0.0/1, 0/1., 0/1.0, some of these, all of these?)

oldvalue

raw-time

1307479476000000

ticket

time

2011-06-08 03:44:36