Hi Alan,

At Wed, 11 Jul 2012 17:28:43 +0800,
Alan Manuel Gloria wrote:
> All right all right, let's use this thread to discuss GROUP, SPLICE,
> Let's call this DEBATE POINT 1, for reasons that are not readily apparent.

I tried to follow your reasoning, but I did not get a concrete image
of the different points. I think I missed code examples…

> GROUP - the original SRFI-49 rule.  The GROUP marker is "invisible"
> when at the start of the line, and is removed, except for its effect
> on indentation - the indentation of that line is still the column
> where the GROUP marker is.  The net effect is that if GROUP is on a
> line by itself followed by a line that is more indented, an extra open
> parenthesis appears.  Otherwise, GROUP does *not* cause an increase in
> nestedness.  I don't remember well, but it was not explicitly
> specified what would happen if group occurs on a line by itself and is
> followed by a line on the *same* indent level - presumably it inserts
> the empty list.  The original GROUP marker was the symbol "group".

With . as group marker:

    a b
  c a

  ((a b))
  (c a)

> SPLICE - a proposed addition to the sweet-expressions 0.2 spec.  The
> SPLICE marker acts differently based on its location (1) at the end of
> a line, the next line's indentation is ignored and it is treated as a
> continuation of the previous line - i.e. "spliced" (2) at the start of
> a line, it is simply ignored (3) in the middle of the line, it is
> treated as a newline followed by an indentation to a column equal to
> the current line's indentation.  It is not explicitly specified, but
> implied that if the SPLICE is on a line by itself, the "end-of-line"
> meaning is invoked rather than "start-of-line".  Originally proposed
> with "\" being the SPLICE marker.

defun \
  a ()
  \ b \ c

(defun a ()
  (b) (c))

> SPLIT - a proposed modification of SPLICE rules that allows
> unification with existing GROUP rules.  The "end-of-line" meaning is
> removed completely, and is interpreted in the same manner as the
> "inline" rule.  SPLIT at the start of the line is ignored (the same
> meaning as SPLICE-at-the-start).  SPLIT-by-itself invokes the
> "start-of-line" meaning.  Variously proposed with "\" or "." being the
> SPLIT marker.

defun a ()
  . b .

defun a ()
  \ b \

(defun a ()
  (b) (c))

    ??? → I don’t understand what it means on its own.

> ENLIST - a proposed modification of GROUP rules that (probably?) gives
> better intuition to the meaning.  ENLIST at the start of a line always
> increases the nestedness of the rest of the line, and if the
> succeeding line(s) are more indented, will have the same nestedness as
> the first line.  Presumably, multiple ENLIST at the start of the line
> also further increase the nestedness, and presumably an "empty" ENLIST
> line (i.e. a line composed only of ENLIST markers) will simply
> increase nestedness of the succeeding line if it is more indented than
> the ENLIST line.  Also presumably, an ENLIST in the middle of a line
> would allow succeeding lines to have multiple, reducing indentation
> levels as long as they more indented than the ENLIST line, although no
> actual concrete specification exists for this behavior.  Originally
> proposed as a reinterpretation of GROUP, renamed in order to separate
> its concepts from GROUP and give better discussion.

    a b
  defun c () \ d

  ((a b))
  (defun c ()

Did I understand that correctly?

I cannot comment on the pros and cons without being sure that I really
understand the rules…

Best wishes,

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