On Fri, Nov 14, 2008 at 7:14 AM, David A. Wheeler <[EMAIL PROTECTED]>wrote:
> Alan Manuel Gloria asked:
> > How about the cond-style if of Arc?
> > (if
> > (condition1)
> > (dothis1)
> > (condition2)
> > (dothis2)
> > (default))
> ...
> > if
> > (condition1)
> > -> (dothis1)
> > (condition2)
> > -> (dothis2)
> > -> (default)
>
> I presume the intent is that "->" at the beginning
> of a line is ignored. Is that what you mean??
> I'll comment based on that possibly wrong assumption,
> please correct me if that wasn't intended.
>
> That _looks_ nice, but two issues:
> 1. That rule would make "->" unusable, which in many apps is really
> important.
> A less-common symbol could work, though, such as "\ ".
True. \ does look nice.
- Show quoted text -
>
> 2. For short pairs that's really awkward. You still have to use 2 lines
> to provide information that in traditional Lisp notation only requires
> one line. For attribute-value pairs that's really important.
>
> For example, given the SMT-LIB example:
> (benchmark bignum
> :source "SMT-COMP'06 Organizers"
> :notes "This benchmark is designed to check if the DP supports
> bignumbers."
> :status sat
> :difficulty "0"
> :category "check"
> :logic QF_RDL
> :extrafuns ((x1 Real))
> :extrafuns ((x2 Real))
> :extrafuns ((x3 Real))
> :extrafuns ((x4 Real))
> :formula
> (and (<= (- x1 x2) (/ 1 1000000000000000000000000000000000))
> (<= (- x2 x3) (/ 1 2000000000000000000000000000000011))
> (<= (- x3 x4) (~ (/ 1 1000000000000000000000000000000000)))
> (<= (- x4 x1) (~ (/ 1 2000000000000000000000000000000012)))))
>
>
> The simple rule "-> ignored at beginning of line" could be used, but that
> would produce:
> benchmark bignum
> :source
> -> "SMT-COMP'06 Organizers"
> :notes
> -> "This benchmark is designed to check if the DP supports bignumbers."
> :status
> -> sat
> :difficulty
> -> "0"
> :category
> -> "check"
> :logic
> -> QF_RDL
> :extrafuns
> -> ((x1 Real))
> :extrafuns
> -> ((x2 Real))
> :extrafuns
> -> ((x3 Real))
> :extrafuns
> -> ((x4 Real))
> :formula
> -> and { {x1 - x2} <= {1 / 1000000000000000000000000000000000} }
> { {x2 - x3} <= {1 / 2000000000000000000000000000000011} }
> { {x3 - x4} <= ~({1 / 1000000000000000000000000000000000}) }
> { {x4 - x1} <= ~({1 / 2000000000000000000000000000000012})}
> )
>
> Yuk. Vertical space is precious; most screens have less vertical than
> horizontal space.
>
> I think we must NOT use "->" as the symbol, anyway.
> So how about "\ " (backslash followed by space)
> as the special symbol? That's rather improbable outside a
> string element; how many times do you need a symbol beginning
> with space or newline?
>
> So here's another rule idea, inspired by that approach.
> When doing indentation processing:
> 1. A "\ " at the beginning of the line (after whitespace) is ignored
> (recursively, so you can have several if you want them).
> 2. INSIDE a line, "\ " means "treat this as a line break,
> with the next line beginning at this same indentation level".
> 3. At the END of a line, "\" means "ignore the newline"; it
> basically merges the line with the next one & ignores indentation.
>
> If we do that, we can write:
>
> ; When condition1, dothis1, etc. are lengthy, you can do this:
> if
> (condition1)
> \ (dothis1)
> (condition2)
> \ (dothis2)
> (default)
>
> ; When condition1, dothis1, etc. are short, you can do this:
> if
> (condition1) \ (dothis1)
> (condition2) \ (dothis2)
> (default)
>
> benchmark bignum
> :source \ "SMT-COMP'06 Organizers"
> :notes \ "This benchmark is designed to check if the DP supports
> bignumbers."
> :status \ sat
> :difficulty \ "0"
> :category \ "check"
> :logic \ QF_RDL
> :extrafuns \ ((x1 Real))
> :extrafuns \ ((x2 Real))
> :extrafuns \ ((x3 Real))
> :extrafuns \ ((x4 Real))
> :formula
> \ and { {x1 - x2} <= {1 / 1000000000000000000000000000000000} }
> { {x2 - x3} <= {1 / 2000000000000000000000000000000011} }
> { {x3 - x4} <= ~({1 / 1000000000000000000000000000000000}) }
> { {x4 - x1} <= ~({1 / 2000000000000000000000000000000012})} )
>
> ; or alternatively:
> benchmark bignum \
> :source "SMT-COMP'06 Organizers" \
> :notes "This benchmark is designed to check if the DP supports
> bignumbers." \
> :status sat \
> :difficulty "0" \
> :category "check" \
> :logic QF_RDL \
> :extrafuns ((x1 Real)) \
> :extrafuns ((x2 Real)) \
> :extrafuns ((x3 Real)) \
> :extrafuns ((x4 Real)) \
> :formula \
> and { {x1 - x2} <= {1 / 1000000000000000000000000000000000} }
> { {x2 - x3} <= {1 / 2000000000000000000000000000000011} }
> { {x3 - x4} <= ~({1 / 1000000000000000000000000000000000}) }
> { {x4 - x1} <= ~({1 / 2000000000000000000000000000000012})} )
>
> ; If you reorder the ":formula" entry you can see why just the "\ at the
> end"
> ; doesn't completely solve the problem. You can't really do that here:
> benchmark bignum
> :logic \ QF_RDL
> :formula
> \ and { {x1 - x2} <= {1 / 1000000000000000000000000000000000} }
> { {x2 - x3} <= {1 / 2000000000000000000000000000000011} }
> { {x3 - x4} <= ~({1 / 1000000000000000000000000000000000}) }
> { {x4 - x1} <= ~({1 / 2000000000000000000000000000000012})} )
> :source \ "SMT-COMP'06 Organizers"
> :notes \ "This benchmark is designed to check if the DP supports
> bignumbers."
> :status \ sat
> :difficulty \ "0"
> :category \ "check"
> :extrafuns \ ((x1 Real))
> :extrafuns \ ((x2 Real))
> :extrafuns \ ((x3 Real))
> :extrafuns \ ((x4 Real))
>
> Hmm, this rule doesn't seem too bad. It's relatively
> simple, and _seems_ useful. I _could_ be convinced.
> Thoughts?
>
Hmm.
if
aprim ast \ expand-prim ast
acond ast \ expand-cond ast
\ do
zap [map expansion _] ast!subx
ast
Not bad.
Sincerely,
AmkG
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