Rel 10

Notices and updates
Post Reply
newdep
Posts: 2019
Joined: Mon Feb 23, 2004 7:40 pm
Location: Netherlands

Rel 10

Post by newdep »

Hi Lutz,

Some questions regarding Rel 10


I dont understand why "setf" was introduced and not "setq" extended
with the features 'setf now has..would that not be more logical?

(breaking the meaning of 'setq is not the case here i think..)



Secondly.. ->
** push now returns the modified list instead of the element pushed. ***

What about lists that extend 100000+ entry's? isnt this then a slowdown factor?



And last ->

Should some function inside newlisp that return 'nil or true not be
changed because of the fact that newlisp now returns "out of bound..."
messages?

i.e.

(not ( '() 1))

should return 'nil and not -> ERR: list index out of bounds in function not

Its somewhat confusing..


Norman.
-- (define? (Cornflakes))

Lutz
Posts: 5279
Joined: Thu Sep 26, 2002 4:45 pm
Location: Pasadena, California
Contact:

Post by Lutz »

I dont understand why "setf" was introduced and not "setq" extended
with the features 'setf now has..would that not be more logical?
'setq' does work like 'setf' now, the second 'setf' naming is a concession to other Lisp dialects. I stopped short of having only one 'set' and abolish all others, perhaps in version 20.0 ;-)
push now returns the modified list instead of the element pushed
'push' returns a reference to the list (like all destructive functions now), so there is no speed penalty returning a big list. Read about reference returns in the 10.0 release notes.

Code: Select all

(not ( '() 1)) ->  -> ERR: list index out of bounds
why is that confusing ( '() 1) ? The empty list has 0 elements, so and index of 1 is out of bounds. The 'not' has nothing to do with this.

newdep
Posts: 2019
Joined: Mon Feb 23, 2004 7:40 pm
Location: Netherlands

Post by newdep »

Yes im studing the Rel 10 notes now.. I must say very nice enhancements!


Well yes ..the 'not..
because from the manual point of view 'not returns 'true or 'nil

like (not '(1)) returns 'nil

so a not on an indexed list returns a string "...out of..." and not 'nil or 'true..

So my point here is that the string syntax-return breaks some default
return values actualy..
-- (define? (Cornflakes))

Lutz
Posts: 5279
Joined: Thu Sep 26, 2002 4:45 pm
Location: Pasadena, California
Contact:

Post by Lutz »

'not' negates the argument, returning 'nil' for everything not 'nil'. But in (not '() 1), 'not' never comes to execute, because the error gets thrown earlier by the inner expression.

Only indices in 'slice' or implicit slicing/resting can be overrun. This is useful for frequent constructs like: "take all elements starting at position idx but now more than size"

newdep
Posts: 2019
Joined: Mon Feb 23, 2004 7:40 pm
Location: Netherlands

Post by newdep »

Thanks..


Btw.. what is this for ? ->

char preLoad[] =
"(define Tree:Tree) (define (Class:Class) (cons (context) (args)))";
-- (define? (Cornflakes))

TedWalther
Posts: 605
Joined: Mon Feb 05, 2007 1:04 am
Location: Abbotsford, BC
Contact:

Post by TedWalther »

Lutz wrote:'not' negates the argument, returning 'nil' for everything not 'nil'. But in (not '() 1), 'not' never comes to execute, because the error gets thrown earlier by the inner expression.

Only indices in 'slice' or implicit slicing/resting can be overrun. This is useful for frequent constructs like: "take all elements starting at position idx but now more than size"
Ok, so can I catch this? That is, is this a catchable error, or do I always have to erect a superstructure of list checking to make sure the reference will succeed? Do you have time to tell us a bit about the design decisions that went into this? Does it make newlisp faster and more efficient?

I was just bit by this feature of newlisp. To this newbie, it seems this behavior violates the principle of least suprise.

TedWalther
Posts: 605
Joined: Mon Feb 05, 2007 1:04 am
Location: Abbotsford, BC
Contact:

Post by TedWalther »

I withdraw my question; I read up on the catch function and everything is hunky dory.

Post Reply