Subject: Re: editor bugs etc.

From: gbergman@UCBBRAHMS (George Mark Bergman)
Date: 25 Jul 83 16:16:52 PDT (Mon)

The following are (i) a short note from Mark Horton
in reply to a note of mine saying I'd been keeping notes
on editor bugs, had heard he had a new version, was
interested in hearing about it and perhaps sending
him notes on bugs not mentioned as corrected; (ii)
a long letter from me in which I do list bugs, features
I think would be desirable etc., (iii) an addendum I
sent the next day, (iv) brief jottings not yet sent.

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>From [email-masked] Thu Jul 21 12:31:55 1983

The new version of vi isn't very different to the user.
The internals use terminfo instead of termcap, but the
user interface isn't affected by this (except that it
starts up faster).  The major new features are
	set showmode
		will cause an indication on the status line when
		you are in input mode
	vedit
		is a new invocation of vi for novices
	more function keys now work
	function keys work in both command and input mode
Of course, there are a few bug fixes too.

There is a binary in ~mark/bin/vi on ucbarpa.  It requires the
/etc/term heirarchy (there is no file called /etc/terminfo) which
was on ucbarpa once but might be gone now.  If you want to grab
them from whereever they still exist, please feel free to try them.
	Mark
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Sent to Mark Horton  23/7/83, about 11AM

Dear Mark,

     Well, your note didn't say you wanted me to send my comments
on editor bugs and suggestions, but you didn't say I shouldn't,
so I decided to do so.  I've tried to organize it into some sort
of sections.  I'd be interested to know which of the bugs mentioned
here you have already found and corrected.  (I may soon find out for
myself; the person in charge of this machine says he'll try to get a
copy of version 3.9 from UCBARPA if they still have it, and get it
running for me.  If you have any helpful information for him, he
is robert@brahms, Robert Gross.)
     Vedit sounds like a great idea.
     I should mention that throughout this letter, I have
avoided using actual control-characters, but faked them,
e.g. used ^ and H to get the appearance of ^H, since files with
real control-characters can be confusing when looked at in mail,
more, etc.  But this means that if you want to try any commands I
refer to that use them, you won't be able to yank and source them,
unless you replace my fakes with real control characters.
     The version I am using is 3.7.

PROBLEMS WITH COUNTS

     Some  vi operations that logically ought to be able to take
counts do not, while others misbehave with counts.  In this section,
``N'' will always denote a positive integer placed as a count before
a vi operation.
     The most gross case of misbehavior is that of N^B!
The effect is to redraw the screen 23N-44 lines further advanced.
(Probably the numbers depend on the screen-size of the terminal;
this is on a Z19, using termcap h19u.)  When N=1, this does indeed
move you a screenful backward, but for higher N it moves the window
forward some amount!  Further, whatever controls are supposed to
monitor whether the command would land one at an acceptable line-
number seem to have a different idea of what it is doing:  If you
aren't already familiar with these weird effects, try setting the
cursor near the end of a file that is more than 4 screenfuls long,
and hitting 3^B.  (You might then try an insert at the place you get
to, and a :f^] .)
     N/pattern/ would be useful, but is not allowed.
     ND would be a natural synonym for dN$, by analogy with NC for cN$,
but it doesn't work that way; it just ignores the N.
     Finally, if N is precisely the number of lines
from the current line to the end of the file,  N$  will still correctly
carry one to the last character of the file, but cN$, NC, dN$ and yN$
refuse to do anything!  (NY does work, not being a synonym for yN$.)
The failure of NC is particularly annoying; often when I am composing
something, I go back to somewhere in the middle of the next-to-
last line, say, and want to rewrite the rest of the sentence;
2cc would kill not only the part I want to rewrite but also the OK
beginning of the line, and 2C or 2c$ won't work.  I realize that I
could get around this by keeping an empty line at the end of the file,
but that should not be necessary.

PROBLEMS REGARDING SOURCE, MACROS, MAPPINGS
     These are enormously useful, but seem to have all kinds of hidden
restrictions.

     The Appendix to the Ex Reference Manual, "List of Changes from
Version 3.5 to Version 3.6" says ``A bug which prevented the source
command from working...from visual has been fixed''.  It is true that
one can now use  :so  from vi, but it still has a bug:  When
the scriptfile invoked contains a global command
and some other command(s) after it, everything after the first global
command is ignored.  The same appears to be true of scripts in named
buffers invoked from vi-bottom-line by  @x.

     (It is, perhaps, unexpected that one can invoke scripts with
multiline commands using @x from vi's bottom-line at all, since such
commands will not work if typed on vi's bottom line directly.
A script like
	s/$/a\
	b
invoked as @x will indeed work.  But strangely, if one tries to
invoke from the regular mode of vi the script
	:s/$/a\
	b
by putting it in buffer x and doing  @x, only the first line
will take effect.)
 
     Another serious restriction is that the command ``vi'' appears to
be ignored in sourced ex-scripts, and though the command Q in macros of
various flavors in vi (mapped characters, map!ed characters that contain
``...^V^[...Q...'';  @x scripts) does take one into ex, any ex
commands after it are ignored.
 
     I assume you are aware of whatever restrictions lead to the
error-message ``Cannot yank inside global/macro'', since you must
have written it, though ``inside'' seems to here have the peculiar
meaning ``after a text-changing operation of the macro.''
     The error-message ``Can't undo in global commands'' is more
mysterious, since I get it when I have a global command after
a text-changing command in an @x script (though not in a sourced file).
     Anyway, the fewer such restrictions these operations were subject
to, the more useful they would be!

     Although nested source commands are allowed (and I find them
useful), they leave the editor in a ``noprompt'' state.  This
can be gotten around by including ``se prompt'' as a line in the
outermost scriptfile, but I would hope the problem causing it could
be cured.

     When one tries to ``:unmap!'' a ``:map!'' command whose
right-hand-side begins with ^H (entered as ^V^H, of course), one
gets the message ``That macro wasn't mapped''.  (One can get around
this by using :unmap! ^V[character].)

     Certain termcaps apparently produce automatic mappings, which
unfortunately may interfere with useful vi commands.  In particular,
on a tvi, ^L gets mapped to a movement command, which makes it
unavailable for redrawing the screen, unless unmapped.

PROBLEMS WITH DIAGNOSTICS

"Hit return to continue" -- It took me a long time to realize that
when I got this diagnostic there was an alternative to hitting
return.  I suggest it be reworded
	"Hit Return or :"
However, the behavior of the editor when this diagnostic is given
seems to be inconsistent.  In particular, when the last of a serious
of commands is
	:e otherfile
and I get "Hit return to continue", then hitting : usually
has no different effect from hitting return (or any other
key), namely the screen is redrawn; yet I think that sometimes
in this situation it has brought me directly to the bottom line
as desired.  Very confusing.
     Would it be possible to have other alternatives than : and return
available, such as /pattern ?  Or, more simply, when one would presently
be given the diagnostic "Hit return to continue", why not just put the
editor into the state it would have if one then hit :, since one would
then still have the option of hitting return and getting into vi
proper, but it would not require the extra keystroke : to
begin a bottom-line command, nor would one go through the frequent
frustrating experience of absentmindedly starting to write a
bottom-line command, or a pattern-search, and then having to wait
while the screen was redrawn because one had hit a key other than :.

"Using open mode"
Again, it took me a long time to learn that when I tried to enter
vi and got this diagnostic, it meant that the system had somehow
lost the termcap for the terminal I was on, and that I would have
to do something to get the correct termcap into the environment.
Till I realized this, I generally ended up either struggling along
frustrated in open mode, or logging out and logging back in.  I suggest
that when someone calls for vi and the termcap is not appropriate,
the editor should not be invoked in any form, but instead, a message
be given such as:
     ``Your environment does not show a termcap entry permitting
the use of the visual editor.  If you are working on a terminal not
supporting vi (in particular, a device with no addressable cursor),
you may enter one of the other modes of the editor with the command
"open filename" or "ex filename".  If you are working on a terminal
that should support vi, your environment entries are incorrect and
should be corrected.  They presently show:
     TERM=....
     TERMCAP=....
If you know the correct name or abbreviation for your terminal-
type, type it at the end of the next line; if not hit return:
     % setenv TERM ''
     If the user typed an acceptable terminal-name, the message would
continue, telling how to get the appropriate termcap.  If the user
instead typed return, the message would ask him or her to type the
name of the manufacturer shown on the terminal, not
worrying about upper/lower-case distinctions, and a list of possible
terminal names and abbreviations would be given... .  This whole
program would not be part of the editor, so there would
be no problem of space within the existing crowded confines of
the editor code.

"No such file or directory" -- I think there should be a distinction
between these two cases, because of the important distinction in the
consequences when the user tries to quit the editor:
If the directory exists, the file is created, but
if not, the results are more complicated -- I seem to recall on one
occasion simply losing what I had written on my second try
at quitting; though I just now did an experiment and this time
repeated ZZ's and :x's simply gave repeated error messages.

"File already exists..." -- The ``List of changes from 3.5 to 3.6'' says
``If you get I/O errors, the file is considered "not edited"... .''
I presume that this correction is somehow the cause of the fact that
I frequently get the above message when trying to leave the editor
on a machine with version 3.7, and have to use
      :w! %|q
to exit.  But I've never seen any evidence that there were I/O errors;
it mainly seems to happen when I've written some lines to another
file in the process of editing.  So the criteria the editor is using
to decide when there have been ``I/O errors'' should be rechecked.

"no such command from open/visual" -- This confused me in my first
few days of using the editor, when I didn't understand that one
couldn't use i and a (in either their vi or ex senses) from the bottom
line of vi.  A message "i -- no such command from open/visual"
was perplexing because I knew that "i" was indeed a vi command.
Perhaps it should say  "no such command from open/visual bottom line".

MISCELLANEOUS PROBLEMS

     In ex search and replacement patterns, \\ is supposed to represent
a real \-character, but something goes wrong when this occurs
at the end of a global command.  E.g., though
     :s/^/\\
works OK (in vi or ex), the variant
     :.g/^/s//\\
definitely does not.  In vi it turns everything off, in ex it seems to
behave as though there were just a single \, and in a scriptfile,
it -- does something still different, which you can discover if you
don't know!

The Ex Reference Manual says, ``For sanity with use from within
visual mode, ex ignores a ":" preceding any command.''  But it
ignores it in the wrong place! -- not at the beginning of the
command line, but just before the command letter itself.  I.e.,
it accepts 1,3:s/^/     /, but not :1,3s/^/    /.

SUGGESTIONS FOR MINOR ADDED CAPABILITIES

   In a multiline substitute command with the "c" option, when
each line is displayed one has three choices: y, n or break.  There
are some further options that would be useful.  One would be "p" --
at present, "p" can only be included on the command line, which
means that one has a choice between seeing the result of every
substitution or none.  In practice, one would generally like to see
the results of the first few cases to make sure that the command one has
written does what one meant it to, and maybe a few tricky cases that
come up; but not every case!   Another might be "u" -- to undo the last
case for which one gave a "y".  Still another might be an option that
would mean ``undo the "c" option -- I see that the substitute command
is doing what I wanted, go ahead and finish it without me.''
    In a command  g/pattern/p,  the pattern in question is occasionally
such that it takes a while to figure out where on the line it occurs.
For this purpose, an option that ``pointed out'' the instance of the
pattern, in the same manner that the pattern to be replaced is pointed
out in substitute command with option c, would be desirable.
    When  g/pattern/p  gives more than a screenful of lines, it would
be nice to have it piped through the equivalent of ``more''.

    ex has the command line option "-", which ``is useful in processing
editor scripts''.  But if one wants to use a script in the course of
an otherwise interactive editing session, it would be desirable to have
a corresponding resettable option ``:se -'' (or ``:se nofb'').

     In strings in pattern-searches, it would be useful to have
^ and $ retain their ``magic'', so that /x[a$]/ could
search for all occurrences of  x  before an  a  or a newline.
(Of course, one would then have to decide whether  /x[^y]/ should
include the case of  x  followed by a newline or not.)

    Just as ex allows the command :vi, so I think that vi should
have some bottom-line command equivalent to the regular-mode
command  Q.  When one has done some text-changing bottom-line
commands, and realizes one wants to go into ex, it can be time-
consuming to hit return and then Q, and wait for the screen to be
redrawn for vi before one gets the ex prompt.

     The option of putting several commands on one line, separated
by, "|" is particularly useful in the vi bottom-line mode, because
it avoids having the screen redrawn several times.  It would be
useful to be able sometimes do the same thing with non-bottom-line
commands, e.g. in editing a troff file at a low baud rate on a dumb
terminal one might like to be able to do  i\fI^]3Ea\fR^]  without
watching the line get redrawn twice.  Perhaps some key that would
cause any sequence of commands to be ``held'' until some complementary
key was hit would be useful.
     It would also be desirable to have a sequence of commands that had
been given in this way available as one unit to be repeated by ``.'',
if desired.

     The parenthesis-matching facility with % might be extended
to match ` with ' and <  with  >.

     I will mention one facility that I discovered by surprize is
possessed by  ed  but not  ex  --  sequences such as  \1  can be used
within  ed  search-patterns.  E.g. (for the most trivial case)
     /\(.\)\1/
will search for doubled letters.

DEBATABLE SUGGESTIONS
     I will mention here some possible changes which have the
difficulty that they would change the meaning of existing commands,
so that it could be argued that the disadvantage of users having
to change their habits might outweigh the advantages.

     First, one might try to resolve, one way or another, the
contradiction between the count arguments taken by the join commands
in  vi and  ex:  In ex, jN joins N+1 lines; in vi, NJ joins N lines
(except if N=1).

     Second, the movement commands  tx  and  Tx  of vi (x any character)
seem poorly defined.  Just as fx will ignore the character on which
the cursor is presently sitting, even if it is an  x,  and move to the
next occurrence, so I would think that  tx  should ignore the character
immediately after the cursor, and  Tx  the character immediately before
the cursor.  The point is that when one does  Nfx,  and finds that one
had failed to count one occurrence of  x  and fallen short of where one
wanted to go, one can hit  ;  and get there.  Likewise, on doing  Ntx
and finding one has fallen short, one should be able to hit  ;  and get
to the the next occurrence; but at present, hitting  ;  leaves
the cursor in the same position; one must hit  ``2;''  to get any
further.  In effect,  Ntx  is presently defined as  Nfxh;  I am
suggesting that it be defined as  lNfxh.

     The sequences  cw, dw  and  yw  are presently violations of the
principle that  c[movement],  d[movement]  and  y[movement]  change,
delete, or yank everything from the current cursor position through
the endpoint of the movement command.  cw does what one would expect of
ce (in fact, they seem to be synonyms), while there is no way to get
the effect which  cw  would have if it were treated ``consistently''.
(E.g., if I have a line beginning  ``And if'', and I want to change it
to ``If'', I cannot just put the cursor on the A and hit  cwI^].)  dw
and  yw  delete up to the character immediately before the point to
which ``w'' would take the cursor.  I would have to agree that this
behavior of dw and  yw  is more useful than that which a literal
interpretation of the movement rule would lead to; but perhaps it
would become still more useful if when applied to the last word on
a line, it deleted or yanked the space immediately before the word
along with the word... .  On the other hand, one could argue for
making a distinction between  cw  and  ce.

     Though I see the motivation for the above definitions,
I see no sensible reason why  Y  should be equivalent to  yy,  when
C  and  D  are equivalent to  c$  and  d$.  I would vote for changing
Y  to mean  y$.

RADICAL SUGGESTIONS

     Is there any reason for maintaining the distinction between
the ``:'' state of vi, and  ex  itself?  At present, there are
relative advantages that lead one to choose to go into one or the
other for a given operation:  From the vi-: state, it is easier
to return to the regular vi state; from ex, one has a more powerful
range of commands; and it is easier to give a series of commands
because each carriage-return gives one a new prompt.  My suggestion
is that from vi, ``:'' should carry you directly to ex, and when you
are in ex, carriage-return (^M) after a command should give you a new
prompt, while ^] should put you into vi.  Conceivably, things might be
simplified even further, and carriage return rather than : could
be the key that would carry one from the regular mode of vi into ex:

			 .-------.	.-------.
	.-------. a,i... | basic |  ^M	|	|
	|  vi   |<------ |	 |----->|  ex	|<---.
	| insert|	 |   vi  |	|	|    |^M
	|  mode | ------>|	 |<-----| mode 	| ---'
	`-------'  ^]	 |  mode |   ^]	|	|
			 `-------'	`-------'

(Of course, ^M presently has a meaning in vi, but
it has a synonym +.)  Clearly, there would also be no need for a
special "Hit return to continue" state.
     I have not distinguished vi and open in the above diagram.
My idea here is that ^] would actually return you to either vi
or open, whichever you had last been in, and that to switch
to the other, you could enter ex and type vi^] or o^] respectively.
(Or you could type  vi^M, respectively o^M, and further ex commands,
and the mode would be saved for the next time you hit a ^].)  Or
alternatively, these could be made settable options: se visual
respectively se novisual.
     Having gotten used to the editor as it now exists, I admit that
I feel uneasy about the above idea -- the sense of knowing that
I am ``still in vi'' when I hit :, and not that ``other land'' of ex, 
represents a kind of of orientation that it is disconcerting
to abandon.  But I can't see any logical disadvantage in making
such a change.  Can you?  Certainly, there would be things that
would have to be thought out, such as what happens to bottom-line
vi pattern-searches.  My thought would be that ``/'' from vi should
give :/ (i.e., put one in ex at the start of a pattern-search),
and ^] after a pattern-search should put one into vi at the appropriate
character on the line, in contrast to ^M after a pattern search,
which would leave one in ex at the appropriate line.  In general,
I think such changes would lead to greater simplicity and learnability
of the editor.
     I would also hope that excursions between vi and ex and back
could be allowed in scriptfiles.  It might also be desirable for
ex to have, in addition to a concept of ``current line'', one of
``current cursor position''... .

     Well, on to another subject.  One of the inconveniences I
found very vexing when first learning to use the editor was that
when in either vi insert mode, or ex/vi-bottom-line, it was very hard
to edit what I was doing.  Within insert mode the only ``editing''
I could do, without escaping, was with the three operations ^H,
^W and the kill character.  And on a slow line with a dumb terminal,
escaping to make changes could be very time-consuming because large
parts of the screen would insist on being redrawn.  Perhaps some
other control-character could serve as
a modified escape, that allowed one to edit what one had entered
in the current insertion without having everything below it redrawn,
and then return to it.  Obviously, if carried to its logical
limit this idea could lead to ridiculous nests of
editing operations; but there would be no need to carry it to its
logical limit.
     Anyway, the problem of editing ex-style commands
was even worse, because there was no way to ``escape and
revise''.  I eventually learned enough to realize that the solution
was to edit complicated commands in another file and source it.
But it is sometimes very useful to have the text on which the
commands are to act in front of you when composing them (e.g., you can
yank and modify various pieces), which led to the variant of writing
command lines within the file I was editing, and then writing
those lines into another file and sourcing that, without ever leaving
the current file.  But this is distracting to deal with
when concentrating on the editing task itself, which led me
to divise a scriptfile which would handle the writing-to-another-file-
and-sourcing for me.  Or actually, several such files:  One for
single-line commands to be used essentially once; one for single-line
commands that I would want to use on the same file during various
editing sessions, and so would want to keep available in that
file, and one for multi-line commands (to be used once).  When
I first got the idea, I thought one scriptfile would be enough, and
I would call it ``do'', so that the command to execute a script I
had written in a file I was editing would be ``:so do''.  The
file it would write to and source would be ``do.again'', so that
if I wanted to reuse it, I could ``:so do.again''.  When I realized
the need for several versions, ``do'' became a directory.  Here,
for your amusement, are the three files.  (Re the lines ``se prompt'',
cf. my comment on that under PROBLEMS WITH SOURCE etc.):

  do/1  (for 1-time use of 1-line commands)
	.w! ~/do/again
	d
	so #
	se prompt

  do/1+  (like above, without deleting the command)
	.w! ~/do/again
	so #
	se prompt

  do/:  (to use this, write a multi-line command script, put : at
  the beginning of the first line, put the cursor on the last
  line of the script, and then source the following:)
	?^:?s/:/
	,''w! ~/do/again
	,''d
	so #
	se prompt

(I also created another version to use in case the script had
to have an internal line beginning with ``:'', so that this couldn't
unambiguously mark the beginning of the script.  This used
a line which explicitly specified the address-range of the script.
But I have never had a need for it, so I will not bother you with it.)
    Finally, having gotten an account on a machine with a version 3
editor recently, I have divised still another way of doing this.  I
have put in my EXINIT the command

	'map ^A "ayy:@a^M'

and now, gratifyingly, the single stroke ^A has essentially the effect
of ``:so do/1+''  -- except for the restrictions to which vi ``map''
commands are subject.  But I've only been using this for a
couple of weeks; so I have yet to learn how chafing those restrictions
will or won't be.
     Anyway, it might be worth thinking about whether some of these
things that I've done with macros should be incorporated in some form
into the editor itself; or else whether these macros might be written
up in the documentation (or some tutorials) on the editor.

     Next subject: Complicated pattern-searches in long files
can be time-consuming.  I have seen the point mentioned
that if a pattern-description can be begun with "^",
this can speed up the search -- since the pattern-comparisons need
only be begun at beginnings of lines.  In some cases, this might
not be possible, but the user might be aware of some other
character or character-sequence in the search-pattern
that will occur relatively rarely in the file.  In such cases it would
be desirable if the user could specify one spot from which the pattern
search should start, working forward and backward from there, to
minimize false starts.  E.g., if for some reason one wants to
delete every word containing the letter m, the script
	%s/[^ ]*m[^ ]*//
would become much less time-consuming if one could mark the point
at which to begin, say writing
	%s/[^ ]*\!m[^ ]*//
so as to instruct the editor to search for m's, and each time
one was found, to find the longest possible strings of non-space
characters before and after it, and delete these.   (This is a silly
example, but I think the idea is clear.)

     Something that I've seriously felt the need for is the
capability of searching for lines that satisfy more than one
condition.  If one just wants to locate such lines, one can
of course leave the editor and do a pipeline of two or
more greps; but it would be nice to be able to perform global
commands on such lines.

    Finally, any possibility of introducing the capability of searching
for patterns including embedded newlines, a la sed?  Multiple windows,
a la emacs?

ADDENDA
     I logged in this morning on an adm3a at 300 baud to go over this
letter once more before sending it, and ran into another bug!  I had
done 15^D to get a large scroll despite the low speed, and at one point
I saw a line with a typo scrolling up.  So I noted its line-number, 402
and without waiting for the screen to stop moving typed something like
402Gfsrd.  What happened was that the change was made on line 407 rather
than 402 -- presumably the cursor was sent to where 402 had been when
the command was received... .
     Editing this letter this morning reminded me of another feature I
have thought would be desirable for editing on dumb terminals at low
speeds:  An option that would cause lines read from a file or typed
in at the bottom of the screen to appear double spaced, with @ signs
@
between them, such as one gets when one deletes a line on such a
@
terminal.  (I have faked this effect here, though the fake will not be
@
very successful if you have  se nu  or  se list  on.)  The point is that
@
editing operations that presently cause painfully slow screen-redrawings
would simply put material in in place of these fillers -- as happens
now when one is lucky enough to be adding material just above a place
where material was previously deleted.

		-  *  -  *  -  *  -  *  -  *  -

    I hope you've found some things of interest in this hodgepodge.

				Yours,
				George (gbergman@brahms)

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23/7/83, about 8PM

     Maybe thinking about the editor while writing my previous
``note'' to you has made me more conscious of these things,
but for some reason, I've discovered several more peculiarities of
the the Version 3.7 editor today!

     First, the abbreviation feature has a strange bug (feature?)
involving the backslash:  If some string X is the abbreviation
for a string Y, and if X is typed (following a space etc)
immediately followed by a \ and another character c, the
result is not Y\c by cY\.  The case where I discovered this
was a doubly complicated one: I had an abbreviation of
the form
	:ab x x\yZ
where x and  y  were characters and Z was a string of characters.  
So when I typed  x,  it presumably first expanded it as x\yZ,
then performed the transformation I just described on the x\y
turning it into  yx\yZ\, and thus giving the result yx\yZ\Z.
This turns out to be one of the cases that can't be unmapped
without doing :una ^Vx.  Further, I just tried a similar case
with x replaced by a string of more than one character
(namely, :ab if if\pq)  and I find I can't unmap that at all.
     I also find that an abbreviated string containing | (which
must be inserted using ^V|, of course) is difficult to unmap.

     Second, some peculiarities about where the cursor ends
up after a yank.  If the yank involved a forward movement,
the cursor stays where it is, which is the beginning
of the yanked segment.  If the yank involves a backwards
movement, the place where the cursor originally was is not
the same as the beginning of the yanked segment, and there
seems to be some confusion as to which principle is followed:
y- or yk moves the cursor up, while yb leaves it fixed.
Unfortunately, there is a snake in the grass with yb: If
you hit p after it, the yanked word will not appear after
the position where the cursor has remained, but
after the position to which it would have gone if it had moved
to the beginning of the yanked segment!  Likewise if you
you hit an x... .
     (You have no idea how much trouble I'm
having with those "if"'s.  Of course, I could quit the editor
and come back in, and I would lose that crazy abbreviation
that way.)

     I also notice that if the cursor is at the end of a word
or between words, 2e behaves the same as e!

     Finally, I note that d^, when the cursor is before the first
nonwhite character, is another exception to the principle that
d[motion] deletes everything through the endpoint of [motion].
Similarly with c^ and y^.

- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *- *
discovered next day (not yet sent):

error with yb does not just concern p and x: any command is
executed as though cursor is at destination of backward in-line
yank.

N^B does not work consistently?  (Not on a medium-length file in Kim)

Can get endless-loop mapping if abbreviation forms word within
abbreviated.  E.g. :ab x ( x )
``word'' must be delimited on left by space, tab,
newline, start-of-insert; on right by any punctuation.  Why
special ``no tail recursion'' rule?
     Things like that ``if'' abbreviation can be undone using
:una i^Vf!

Mention desirability of Np

copies sent to ralph@ucbarpa, lindahl@topaz 25/7/83