[TUHS] mail (Re: off-topic list

[Larry McVoy]

On Mon, Jun 25, 2018 at 12:44:15PM +1000, George Michaelson wrote:
> your email Lyndon, was uncannily like what I wanted to say. I think.
> 
> a) (n)MH is great
> b) I can't live in one mail UI right now for a number of reasons.
> Thats unfortunate
> 3) integration of MH into pop/imap was abortive and requires effort.
> If thats improved, I'd love to know

I use rackspace for mcvoy.com but plain old mutt for reading it here
and sending.  I use fetchmail to get the mail locally.  Works for me
because mcvoy.com used to be a mail server and is still set up from
those times to send mail.  Kind of hacky but rackspace does the spam
filtering and I got sick of babysitting that.

> 4) we stopped advancing the art (tm) for handling data via pipes and
> grep-like workflows

So the source management system I started, BitKeeper, has sort of an
answer for the processing question.  It's a stretch but if you look 
at it enough a mail message is a little like a commit, they both have
fields.

Below is an example of the little "language" we built for processing
deltas in a revision history graph.  Some notes on how it works:

	:SOMETHING: means take struct delta->SOMETHING and replace the
	:SOMETHING: with that value.

	Control statements begin with $, so $if (expr).
	From awk we get $begin and $end (this whole language is very awk
	like with what awk would consider a line we hand the language
	a struct delta.)

	We invented a $each(:MULTI_LINE_FILE:) {
		:MULTI_LINE_FILE:
	}
	that is an interator, the variable in the body evaluates to 
	the next line of the multi line thing.  Weird but it works.

	$json(:FIELD:) json encodes the field.

	"text" is just printed.

	We gave you 10 registers/variables in $0 .. $9, they default to
	false.

This little script is running through each commit and printing out the
information in json.  Examples after the script.

It's important to understand that the $begin/end are run before/after
the deltas and then the main part of the script is run once per delta,
just like awk.

# dspec-v2
# The dspec used by 'bk changes -json'

$begin {
	"[\n"
}

$if (:CHANGESET: && !:COMPONENT_V:) {
	$if($0 -eq 1) {
		"\},\n"
	}
	"\{\n"
	"  \"key\": \":MD5KEY:\",\n"
	"  \"user\": \":USER:\",\n"
	"  \"host\": \":HOST:\",\n"
	"  \"date\": \":Dy:-:Dm:-:Dd:T:T::TZ:\",\n"
	"  \"serial\": :DS:,\n"
	"  \"comments\": \"" $each(:C:){$json{(:C:)}\\n} "\",\n"
        $if (:TAGS:) {
             "  \"tags\": [ "
             $each(:TAGS:){:JOIN:"\""(:TAGS:)"\""}
             " ],\n"
        }
        "  \"parents\": [ "
            $if(:PARENT:){"\"" :MD5KEY|PARENT: "\""}
            $if(:PARENT: && :MPARENT:){," "}
            $if(:MPARENT:){"\"" :MD5KEY|MPARENT: "\""}
            " ]\n"
	${0=1}		 		# we need to close off the changeset
}

$end {
	$if($0 -eq 1) {
		"\}\n"
	}
	"]\n"
}

So here is human readable output:

$ bk changes -1
ChangeSet at 1.2926, 2018-03-12 08:00:33-04:00, rob at bugs.(none)
  L: Fix bug where "defaultx:" would be scanned as a T_DEFAULT
  followed by a T_COLON. The "x" and anything else after
  "default" and before the colon would be ignored.
  
  So if you ever had an option name that began with "default",
  it wouldn't be scanned correctly.
  
  This bug was reported by user GNX on the BitKeeper user's forum
  (Little language area).

And here is the same thing run through that scrip above.

$ bk changes -1 --json
[
{
  "key": "5aa66be1MaS_1t5lQkNCflPexCwd2w",
  "user": "rob",
  "host": "bugs.(none)",
  "date": "2018-03-12T08:00:33-04:00",
  "serial": 11178,
  "comments": "L: Fix bug where \"defaultx:\" would be scanned as a T_DEFAULT\nf
ollowed by a T_COLON. The \"x\" and anything else after\n\"default\" and before 
the colon would be ignored.\n\nSo if you ever had an option name that began with
 \"default\",\nit wouldn't be scanned correctly.\n\nThis bug was reported by use
r GNX on the BitKeeper user's forum\n(Little language area).\n",
  "parents": [ "5a2d8748bf8TYIOquTa3CZInTjC7KQ" ]
}
]


If you have read this far, maybe some ideas from this stuff could be used
to get a sort of processing system for structured data.  You'd need a plugin
for each structure but the harness itself could be reused.