[REBOL] Re: Web site update
From: g:santilli:tiscalinet:it at: 1-Jul-2004 16:42
Hi Ladislav,
On Thursday, July 1, 2004, 3:43:16 PM, you wrote:
LM> 2. A BUILD-FUNC dialect added and used to innovate the CFUNC closure
LM> creating function. Improvements: the CFUNC implementation using
LM> BUILD-FUNC is now 40% simpler and 20% faster (shameless plug :-). BTW, I
LM> heard some rumours that there are other implementations of closures in
LM> Rebol. Could the respective authors compare their algorithms with this one?
Mine is surely slower because it isn't using the nice trick you
are using. :-)
#do [document {
GET-ALL takes a block of words (only WORD!s) and returns a block
with the respective values. For example:
a: 1
b: 2
get-all [a b] ; == [1 2]
The difference with REDUCE is that GET-ALL does not evaluate (just
uses GET/ANY).
}]
get-all:
func [
"Get (without evaluating) all words in a block" [catch]
words [block!]
] [
words: copy words
if not parse words [any [words: word! (change/only words get/any words/1)] end] [
invalid-argument pick words 1
]
head words
]
#do [document {
LOCALIZE (which probably needs a new name) is just like USE,
except that keeps the values of the words it makes local.
Example:
a: 1
b: 2
localize [a b] [
; here a = 1 and b = 2
b: 3
]
; b is still 2 here
}]
localize:
func [
"Defines words local to a block, but keeps their value" [catch]
words [block!]
body [block!]
] [
use words reduce [
'set copy words throw-on-error [get-all words]
'do body
]
]
#do [document {
CLOSURE creates functions with a dynamic context. It can be used just
like FUNC, except that it creates a new context at each invocation
of the function.
}]
closure:
func [
"Defines a closure with given spec and body." [catch]
spec [block!] "Help string (opt) followed by arg words (and opt type and string)"
body [block!] "The body block of the closure"
/local word words
] [
words: make block! 2 + length? spec
parse spec [
any [
set word [word! | refinement!] (insert tail words to word! word)
| skip
]
]
throw-on-error [
make function! spec reduce [
'localize words 'copy/deep body
]
]
]
Regards,
Gabriele.
--
Gabriele Santilli <[g--santilli--tiscalinet--it]> -- REBOL Programmer
Amiga Group Italia sez. L'Aquila --- SOON: http://www.rebol.it/
