Thanks for the detailed comments Sudarshan!

On Mon, Oct 23, 2017 at 12:12 AM, Sudarshan S Chawathe <xxxxxx@eip10.org> wrote:

- Caveat: My testing of the reference implementation is based on
manually pulling files out of the Chibi Scheme repository by
examining dependencies starting from show.sld, so I may have
missed something. (Is there an easier way?)

There is a somewhat out of date snow-fort package for ease of

testing, which will be brought up to date before finalization:

http://snow-fort.org/pkg/

You're right that there are some missing/changed procedures in

the reference implementation, mostly last minute draft changes.

Assume the draft is correct - I'll update the implementation shortly.

- In 'escaped': Do quote-ch and esc-ch default to #\" and
#\\ resp.?

Good catch, yes, I'll document this.

Also, would it be useful to permit the renamer
procedure to map a character to more than one character?

Out of curiosity, do you have a use case in mind?

Strings are probably better regardless.

- In 'numeric/si', should there be a space between the numeric and
suffix parts of the resulting string? I think including a space
is the SI recommendation (but I am not sure). It may be useful
to have an option for such a space, if it is not the default.

I think in program output it's most common to not include a space

(e.g. any gnu -h command-line option), but can add support for this.

- In space-to.: Perhaps obvious by Scheme conventions, but a brief
note that columns are numbered starting at 0 may be worthwhile.
Also, is it an error (or a no-op?) if the column argument is not
a nonnegative integer?

This is actually counter-intuitive by vt100 conventions which are 1-based,

so I'll make the 0 indexing clear. Yes, invalid inputs should be a domain

error.

- Padding: In the implementation, padded and padded/right produce
identical results, matching those shown for padded/right in the
description. I found that padded/left seems to do what the
description says padded does.

A pre-draft change suggested by John Cowan to match SRFI 13,

again, the draft is correct.

- For trimmed/both and fitted/both, does 'width' have to be at
least *twice* the width of 'ellipses'? The current
implementation raises an error if not.

Yes, this is needed so that it's possible to insert the ellipsis on both

the left and right. Although I suppose we could special case and

just use a single ellipsis if it's that narrow.

- In trimmed etc., is it true that the fmts are invoked in
left-to-right order only as needed. (The description seems to
indicate so.)

Yes.

- Will the optional extensions in Columnar Formatting have a
suggested library name or other easy way for detection? Also,
are these the only optional parts, or are there others (color,
unicode, etc.)?

Good question - I think we should split out the core from three

extensions (columnar, pretty, color + unicode). The (srfi 159)

library, also to be provided as (scheme show), will export everything.

- For columnar, is it true that in cases where 'width' (e.g., 78)
is not divisible by the number of columns (e.g., 5), the extra
space is allocated column-wise left to right (e.g., 16, 16, 16,
15, 15)?

Yes, I'll clarify that.

- For wrapped, would it be useful to accept an optional
splitting-predicate to use instead of the default
char-whitespace? We could use wrapped/list in such cases, but
then we give up incremental output.

Good point, let me add this.

- Minor

- The implementation section has a link to code.google.com which
forwards to github. Given the status of code.google.com, perhaps
another URL (via synthcode.com perhaps) is preferable.

Sorry, the code is at https://github.com/ashinn/chibi-scheme/blob/master/lib/chibi/show.sld.

I'll update this with the full list of files needed.

Alex