Topic: The Function Function

[Rustabout]

I don't 100% understand what the AutoLISP developer reference guide means when it states that the 'function' function optimizes the lambda expression. Is it somewhat of a relic for when LISP routines didn't run quite as fast as they do now? Do people here still use it in their code? It's a hard function to search for help on for obvious reasons

Cheers!

[VovKa]

Do people here still use it in their code?

i always do

[JohnK]

... It's a hard function to search for help on for obvious reasons

You've always got ours. Ours isn't as flashy as the Autodesk version but it helps. I haven't updated it in years either but it still has a ton of good info.
https://www.theswamp.org/Sources/doc/avlisp/#function

[Grrr1337]

I've got small interesting observation from your question,
function converts any literal value into a symbol type, and any lambda function into a LIST type -

Code - Auto/Visual Lisp: [Select]

1. _$ (function mapcar)
2. MAPCAR
3. _$ mapcar
4. #<SUBR @0000006ba3ccea98 MAPCAR>
5. _$ (type (function mapcar))
6. SYM
7. _$ (function abc)
8. ABC
9. _$ (set (function abc) "hello world")
10. "hello world"
11. _$ abc
12. "hello world"
13. _$ (function (lambda (x) x))
14. (quote #<USUBR @0000006bd150fcf0 -lambda->)
15. _$ (type (function (lambda (x) x)))
16. LIST
17. _$ (type (lambda (x) x))
18. USUBR
19.  

[gile]

I've got small interesting observation from your question,
function converts any literal value into a symbol type, and any lambda function into a LIST type -

You should compare function with quote, as when we do:
(macar '(lambda (x) ...) ...) or (macar (quote (lambda (x) ...)) ...)
vs
(macar (function (lambda (x) ...)) ...)

Code - Auto/Visual Lisp: [Select]

1. _$ (function (lambda (x) x))
2. (quote #<USUBR @000001eb96e3b138 -lambda->)
3. _$ (quote (lambda (x) x))
4. (LAMBDA (X) X)
5. _$ '(lambda (x) x)
6. (LAMBDA (X) X)

[d2010]

If you must learn Java or C# , then you can try this newcode.txt, for teaching Csyntax, gramarlyC++,whole C+=source.
You  can convert this newcode.txt to 100%Vlisp.
http://lisp2arx.3xforum.ro/viewtopic.php?pid=168#168
Do not waste your-time with lambda, because the function+lambda not exists
in Java or JavaScript.?!

[VovKa]

Do not waste your-time with lambda

i've been doing lisp for quite a while and i must say that it covers 99% of my needs
and i've never thought of switching to smth else

[gile]

'function' is to 'quote' what 'defun' is to 'defun-q'.

Code - Auto/Visual Lisp: [Select]

1. (setq a '(lambda (x) (* x x)))
2. (setq b (function (lambda (x) (* x x))))
3. (defun c (x) (* x x))
4. (defun-q d (x) (* x x))

Code: [Select]

_$ a
(LAMBDA (X) (* X X))
_$ b
(quote #<USUBR @000001eb9681c890 -lambda->)
_$ c
#<USUBR @000001eb96d17930 C>
_$ d
((X) (* X X))

Code: [Select]

_$ (benchmark '((apply a '(2)) (apply b '(2)) (apply 'c '(2)) (apply 'd '(2))))
Benchmarking ...................Elapsed milliseconds / relative speed for 65536 iteration(s):

    (APPLY B (QUOTE (2))).............1656 / 1.93 <fastest>
    (APPLY (QUOTE C) (QUOTE (2))).....1688 / 1.90
    (APPLY A (QUOTE (2))).............2969 / 1.08
    (APPLY (QUOTE D) (QUOTE (2))).....3203 / 1.00 <slowest>

[MP]

I wonder how many times benchmark has been run over the  years.

[JohnK]

MP, was that utility, you wrote, ever released on the newsgroups (or elsewhere: where were after the newsgroups and before here)? The reason I ask is because I was just wondering where else it is so widely used (besides here).

[MP]

The version that is used at the swamp - not my first benchmarker - was penned in 2005 - a year after I quit frequenting Autodesk’s discussion forum and joined - and participated exclusively - at the swamp. I’ve seen code I’ve written show up in other countries - never mind discussion forums - as early as the late 90s - yes, getting old as fk - so it's likely used elsewhere - but I've never attempted to identify where.

[It's Alive!]

If you must learn Java or C# , then you can try this newcode.txt, for teaching Csyntax, gramarlyC++,whole C+=source.
You  can convert this newcode.txt to 100%Vlisp.
http://lisp2arx.3xforum.ro/viewtopic.php?pid=168#168
Do not waste your-time with lambda, because the function+lambda not exists
in Java or JavaScript.?!

C++ has std::function &  lambda expressions  https://en.cppreference.com/w/cpp/utility/functional/function

[Rustabout]

I stumbled upon this by chance when looking for something else:

https://www.cadtutor.net/forum/topic/47217-lambda-function-mapcar-apply-foreach-explained/

There's a very useful explanation of the 'function' function in regards to optimization towards the end of that discussion.

I appreciate all the explanations! I'm still a bit confused... but that's due to my own deficiencies rather than the quality of the explainations you've posted above. I figure If I review all the posts with a fresh cup of coffee I'll be all sorted out; thanks everyone!!

[baitang36]

please see http://www.theswamp.org/index.php?topic=56121.0