[REBOL] QUOTE (useful but missing)
From: robbo1mark::aol::com at: 12-Dec-2001 5:05
here's an old Lisp / Scheme style function
which is missing in REBOL but turns out
to be pretty useful for delaying evaluation
and defining words to evaluating expressions
or in REBOL parlance paren!'s.
here's the function definition,
QUOTE: func ['value] [return :value]
and here's some examples of it's use.
>> a: 7
== 7
>> quote a
== a
above example same as lit-word! 'a no immediate
benefit, however consider this,
>> a: quote (print "hello world")
== (print "hello world")
>> a
hello world
>> :a
== (print "hello world")
In the above example we set the word 'a to an
evaluating expression ie a paren!
This is useful as these kind of paren!'s can
in certain circumstances be used in place of
a 'DOES function with an increase gain in speed
of 40 to 50 percent, the speed gain of course
is due to avoiding the function call. Note this
is only useful in replacing functions without
any arguments or local words.
The notational tick ' for lit-words is really just
shorthand for quote value, it would be nice if we
could have extended literal notation for other types
of values in REBOL 3.0.
ie literal-paren! '()
example
>> '(print "hello")
== (print "hello")
hope you find this useful,
cheers everybody,
Mark Dickson
