Core lexical syntax Lassi Kortela (25 Sep 2019 10:15 UTC)
Re: Core lexical syntax John Cowan (25 Sep 2019 14:09 UTC)
Machines vs humans Lassi Kortela (25 Sep 2019 14:25 UTC)
Re: Core lexical syntax Alaric Snell-Pym (25 Sep 2019 15:44 UTC)
Re: Core lexical syntax John Cowan (25 Sep 2019 19:18 UTC)
Mechanism vs policy Lassi Kortela (25 Sep 2019 19:58 UTC)
Re: Mechanism vs policy Arthur A. Gleckler (25 Sep 2019 21:17 UTC)
Re: Mechanism vs policy Lassi Kortela (26 Sep 2019 07:40 UTC)
Re: Mechanism vs policy John Cowan (25 Sep 2019 22:25 UTC)
Re: Mechanism vs policy Arthur A. Gleckler (26 Sep 2019 01:34 UTC)
Limits, symbols and bytevectors, ASN.1 branding Lassi Kortela (26 Sep 2019 08:23 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding Alaric Snell-Pym (26 Sep 2019 08:56 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding John Cowan (27 Sep 2019 02:38 UTC)
ASN.1 branding Lassi Kortela (27 Sep 2019 14:56 UTC)
Re: ASN.1 branding Alaric Snell-Pym (27 Sep 2019 15:24 UTC)
Re: ASN.1 branding Lassi Kortela (27 Sep 2019 18:54 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding John Cowan (27 Sep 2019 01:57 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding Lassi Kortela (27 Sep 2019 16:24 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding John Cowan (27 Sep 2019 17:37 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding Lassi Kortela (27 Sep 2019 18:28 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding John Cowan (27 Sep 2019 18:39 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding Lassi Kortela (27 Sep 2019 18:46 UTC)
Re: Limits, symbols and bytevectors, ASN.1 branding John Cowan (27 Sep 2019 21:19 UTC)
Re: Mechanism vs policy Alaric Snell-Pym (26 Sep 2019 08:45 UTC)
Implementation limits Lassi Kortela (26 Sep 2019 08:57 UTC)
Re: Implementation limits Alaric Snell-Pym (26 Sep 2019 09:09 UTC)
Re: Implementation limits Lassi Kortela (26 Sep 2019 09:51 UTC)
Meaning of the word "format" Lassi Kortela (26 Sep 2019 10:31 UTC)
Stacking it all up Lassi Kortela (26 Sep 2019 11:05 UTC)
Brief spec-writing exercise Lassi Kortela (26 Sep 2019 11:46 UTC)
Re: Brief spec-writing exercise John Cowan (26 Sep 2019 15:45 UTC)
Standards vs specifications Lassi Kortela (26 Sep 2019 21:24 UTC)
Re: Standards vs specifications John Cowan (27 Sep 2019 04:29 UTC)
Re: Standards vs specifications Lassi Kortela (27 Sep 2019 13:47 UTC)
Re: Standards vs specifications John Cowan (27 Sep 2019 14:53 UTC)
Re: Meaning of the word "format" John Cowan (26 Sep 2019 20:59 UTC)
Re: Meaning of the word "format" Lassi Kortela (26 Sep 2019 21:09 UTC)
Re: Meaning of the word "format" John Cowan (27 Sep 2019 02:44 UTC)
Length bytes and lookahead in ASN.1 Lassi Kortela (27 Sep 2019 13:58 UTC)
Re: Length bytes and lookahead in ASN.1 John Cowan (27 Sep 2019 14:22 UTC)
Re: Length bytes and lookahead in ASN.1 Alaric Snell-Pym (27 Sep 2019 15:02 UTC)
Re: Length bytes and lookahead in ASN.1 hga@xxxxxx (27 Sep 2019 15:26 UTC)
(missing)
Fwd: Length bytes and lookahead in ASN.1 John Cowan (27 Sep 2019 16:40 UTC)
Re: Fwd: Length bytes and lookahead in ASN.1 Alaric Snell-Pym (27 Sep 2019 16:51 UTC)
Re: Fwd: Length bytes and lookahead in ASN.1 John Cowan (27 Sep 2019 17:18 UTC)
Length bytes and lookahead in ASN.1 hga@xxxxxx (27 Sep 2019 16:58 UTC)
Re: Length bytes and lookahead in ASN.1 John Cowan (27 Sep 2019 17:21 UTC)
Re: Mechanism vs policy John Cowan (27 Sep 2019 03:52 UTC)
Re: Core lexical syntax Alaric Snell-Pym (26 Sep 2019 08:36 UTC)
Re: Core lexical syntax John Cowan (25 Sep 2019 14:13 UTC)

Re: Length bytes and lookahead in ASN.1 Alaric Snell-Pym 27 Sep 2019 15:02 UTC
On 27/09/2019 15:22, John Cowan wrote:
> I think the first method is clearly superior.  Of the usual data
> structures, only lists normally take O(n) time to get the length.  In any
> case, R7RS `write` already has to do this in order to know where to insert
> datum labels.

Yeah. Implementation tip: memoize sub-sequence lengths, otherwise
writing ((1)) works out the length of (1) to write the length for the
whole expression, then again to write the length for the (1) expression,
as it were.

As for the larger issue of whether compound objects should have a byte
length or an elements-length:

Code to write with element-counts only needs to spend O(length of list)
rather than O(number of atoms in entire subexpression) scan, without
needing that memoization code: this means less code and less working RAM
used on encoding.

Code to read with element-counts needs to recurse through all the
sub-expressions to find the end, and can't just skip it.

If skipping parsing subexpressions isn't a desired feature, then
element-counts win; so is skipping subexpressions at read time desired?

--
Alaric Snell-Pym   (M7KIT)
http://www.snell-pym.org.uk/alaric/