Hi Tomas,
> 'run' is more general and evaluating version, i.e. it's a function
> suitable for manipulating programs (aka eval) with other bell and
> whistles like "environment control". 'prog' is a "macro", i.e. a
> convenience shortcut for writing text of a program by hand. You can
> build the macro version on to of the evaluating version.
Thanks for the explanation!
I would not use the term "macro" in this case, however. You had also
used it, btw, in a similar context in a previous mail.
To my understanding, a "macro" is a piece of code which is processed (by
a (pre)compiler or an equivalent software), resulting in a _new_ piece
of code which is then used instead.
The first macro I encountered was the pre-defined REPT macro in some
assemblers (terminated by ENDM for "end macro"). Writing
rept 4
sal ax,1
rcl si,1
endm
is the same as writing
sal ax,1
rcl si,1
sal ax,1
rcl si,1
sal ax,1
rcl si,1
sal ax,1
rcl si,1
In C, a macro like
#define Push(c,x) (data(c)=(x), Save(c))
when called as
Push(c1, foo(*p++) + bar(mumble()));
expands to
data(c1)=(foo(*p++) + bar(mumble())),
Save(c1);
This is what the C compiler sees and compiles.
I understand what you mean. In Common Lisp, you would need to write a
macro to implement 'prog'.
In PicoLisp, as you know, 'prog' is a function. There is no processing
taking place, at any time, which would transform the body of 'prog' into
some other form. Instead, it is executed directly.
There is a 'macro' (in the above sense) function in PicoLisp.
(de macro "Prg"
(run (fill "Prg")) )
It takes an executable body (list of expressions) in "Prog", processes
it with 'fill' (which results in a modified list), and then uses that
result for execution (running it).
Cheers,
- Alex
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