bug#18932: string->number errors on e.g. "1e400xyz"

bug#18932: string->number errors on e.g. "1e400xyz"

["Taylan Ulrich Bayırlı/Kammer"]

When string->number is given a number in scientific notation with a
very high exponent, it errors with "value out of range."

I don't know if that is acceptable, but what seems unacceptable is
that it errors even if the string contains further characters and is
thus not a valid number; R5RS says that #f should be returned when the
string does not contain a syntactically valid number, and R7RS adds
explicitly that string->number never signals an error due to the
contents of the given string.

Apparently MIT/GNU Scheme has the same bug, as reported by 'ecraven'
on #scheme.  From other systems I tested, Racket, Gauche, Gambit, and
Chibi return +inf.0 for numbers with a too high exponent; I'm told
Chicken also does so when the "numbers egg" is loaded.

Taylan

bug#18932: #18932 string->number errors on e.g. "1e400xyz"

[guile]

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Note that guile 2.0.11 also gives strange results for large negative exponents:
scheme@(guile-user)> (string->number "1e-400")ERROR: In procedure string->number:ERROR: In procedure string->number: Value out of range: -400
 
For comparison, in Scheme 48 1.9
(string->number "1e-400") => 0.0
(string->number "1e400") => +inf.0
(string->number "1e400xyz") => #f

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bug#18932: [Anand Mohanadoss] symbol printing problem

[Andy Wingo]

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From: Anand Mohanadoss <anand108@gmail.com>
To: guile-user@gnu.org
Subject: symbol printing problem
Date: Mon, 8 Aug 2016 18:04:45 +0530
Message-ID: <CAFNjtaD8DESceh0ZMEBWb=9PqUhNG_onk8ycb8EL-6eDaQJaNA@mail.gmail.com>

Hi,

We observed the following with guile 2.0.11 -

scheme@(guile-user)> (define sym '912828S7912810RS)
While reading expression:
ERROR: In procedure string->number: Value out of range: 7912810

Is this expected?  Do we need to enable any read-options?  If this is
expected, it appears that if we are creating symbols from random data, we
need to do a symbol->string before printing it.  Is this the recommendation
or should we do something else?

Thank you!
Anand

bug#18932:

[Jonathan Theodore Mayer]

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The lowest and highest exponent that do not result in an error for
string->number are -324 and 308, respectively. I am running Guile 2.0.9.

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