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7:43:35
trittweiler
unanimousarc, Yeah, there's a way around that involving make-load-form but it's really quite advanced,I would suggest you to just go with MAKE-PERSON instead of the #S(...) notation. Note that the #S(...) notation would also create a read-only object.
7:45:26
phoe
There are several "times" in Lisp that are basically reader/compiler/etc. passes from raw text to actual Lisp code and data.
7:46:07
phoe
The file compiler's role is to grab Lisp forms, turn them into code and dump all of the resulting code into compiled files.
7:46:56
phoe
#S(person ...), when it's read, actually results in a Lisp *instance*. The reader turns it into an instance of PERSON.
7:47:42
phoe
The file compiler does just fine with lists, code, functions, and so on. But it chokes on actual instances of objects, for a good reason.
7:47:57
unanimousarc
hm, I'll have to read more about this compilation stuff eventually, for now I'll just treat lisp like an interpreter
8:28:19
no-defun-allowed
AeroNotix: [here is cl-decentralise in its god awful hackish form](https://gitlab.com/Theemacsshibe/cl-decentralise)
9:53:28
phoe
AeroNotix: you should make it possible to declare what the delimiter is. It should be possible to customize the delimiter, just like in HTTP content-type multipart/form-data. It has a custom boundary.
10:20:16
beach
v0|d: Because most modern garbage collectors don't touch objects that are no longer live. Such collectors could not call any destructor for dead objects.
10:21:30
beach
v0|d: Some Common Lisp implementation have what is known as "finalizers" that can accomplish some of what a destructor does. However, it is still not predictable when the garbage collector will detect that an object is no longer live.
10:21:32
Zhivago
The more important point is that by the time the object is collected it is no-longer reachable by a destructor. If it were, it could be re-linked into the graph by the destructor. Leading to things like resurrecting objects from the dead (once only) in Java.
10:22:55
Zhivago
Finalizers get around this by not operating on the dead object, but usually share some (still live) substructure.
10:24:57
heisig
v0|d: You could, however, implement your own generic function (destroy-instance X), which would internally do a (change-class X 'destroyed). Then CLOS would have destructors :) Of course this would be unrelated to the GC.
10:34:06
phoe
the basic use case for a destructor is freeing resources - Lisp has garbage collection instead.
10:34:27
phoe
another basic use case is closing closeable resources when they are no longer used - Lisp has WITH-* macros for that.
10:35:51
phoe
yet another use case is closing closeable resources that isn't limited to the dynamic scope of an object, so WITH-* macros can't help you there - and, for that, you can write an ordinary function in Lisp.
10:37:19
heisig
You forgot another use case - accidentally breaking your program. That is why I proposed DESTROY-INSTANCE :)
10:37:48
v0|d
Zhivago: Is it possible to detect for a compiler that a user defined finalizer can ressurect objs?
10:40:24
Shinmera
Because the finalizer stays alive due to the object and the object stays alive due to the finalizer
10:40:56
Shinmera
GCs protect against double frees and forgetting to free, but you can still create memory leaks.
10:41:27
phoe
the finalizer must be registered in the GC-accessible location somewhere, so GC knows to fire it when the collection occurs
10:41:42
phoe
And if the finalizer is registered in a live location, then the object it closes over is also live
10:42:17
phoe
if A closes over B and B closes over A, then both of them are dead if neither of them is accessible
10:42:46
phoe
so "the finalizer stays alive due to the object and the object stays alive due to the finalizer" is not enough to proclaim the object or the finalizer alive.
10:45:57
Shinmera
It's not necessarily the case that a finalizer is registered as a root, it just needs to be treated specially since, yes, usually cyclic references in objects are freed just fine.
10:46:49
phoe
Yep - it doesn't really have to be registered anywhere, but the GC needs to know where it is and how to fire it.
11:10:28
beach
no-defun-allowed: It's because, for some reason, people don't use Emacs abbrevs. Don't ask me why.
11:14:48
heisig
From the spec: "A girlfriend is a function whose behavior depends on the classes or identities of the arguments supplied to it." Well put :)
11:25:17
phoe
No doubt that Lisp isn't all that popular if Lisp programmers finalize their girlfriends
11:25:45
beach
jackdaniel: Then they should use the equivalent of Emacs abbrevs in the IRC client they are using.
11:34:56
heisig
Does anyone know a good library for type inference in Lisp? I'd like to have something like (infer-type 'cl:floor 'double-float) -> '(integer double-float).
11:35:58
no-defun-allowed
There's a chatroom with two other lispers, me and her and she hasn't been converted yet.
11:38:37
v0|d
no-defun-allowed: according to the definition, try supplying a proper argument to her.
11:56:11
TMA
no-defun-allowed: and then the old girlfriend would be garbage collected and possibly finalized. may I suggest CHANGE-CLASS instead?
13:01:50
hjudt
why do some programmers use keyword prefixes in loop? e.g. (loop :with manual-names...)
13:21:30
heisig
phoe: I already considered using SBCL internals. But I also like to have things portable. Maybe a mix of both.
13:25:01
pjb
hjudt: this is because loop keywords are not exported from CL. Therefore they can be exported from other packages.
13:26:06
pjb
hjudt: in that case, if you write a loop in your package without using KEYWORD, you intern symbols with those names in your package. Then if you use-package the package that exports symbols with the same name, you get collisions!
13:28:24
phoe
(loop #.(make-symbol "FOR") i #.(make-symbol "IN") '(1 2 3 4 5) #.(make-symbol "DO") (print i))
13:28:29
pjb
and for the people who find that loop is not lispy enough, using KEYWORDS instead of symbols makes it look more or less like an operator with &key arguments :-)
13:41:20
phoe
Something that would allow me to (trivial-ftype:function-ftype #'phase) ;=> (FUNCTION (T) (VALUES (OR (DOUBLE-FLOAT -3.141592653589793d0 3.141592653589793d0) SINGLE-FLOAT) &OPTIONAL))
13:44:11
AeroNotix
It's already one of the most unreadable forms you can use, anything to make it more readable helps
13:50:41
heisig
AeroNotix: In Petalisp (https://github.com/marcoheisig/Petalisp), I JIT-compile array definitions to fast specialized code. To do so, I need to know that adding floats produces floats and so on.
13:52:52
heisig
Ideally, I could also use type inference to prevent code like (+ "foo" 5) from ever being run. Run-time errors in distributed systems are not pretty.
15:43:48
ym
Is there any tool to visualize AST/ASG of LISP code so that it would be displayed as interactive graph like in modern visual programming DSLs?
15:45:38
slyrus1
scymtym: thanks! do you have a preference for merging the PR vs just pushing a (cleaned up) commit to master?
15:45:48
phoe
ym: I somehow don't find the right side of https://raw.githubusercontent.com/cuichaox/visual-cells/master/demo/slime-screenshot.png readable at all
15:46:55
phoe
it's a good way of turning four lines of readable code into half a screen of unreadable graph, as you can see above.
15:47:21
phoe
AudioMulch graphs look like https://dt7v1i9vyp3mf.cloudfront.net/styles/news_large/s3/imagelibrary/A/AudioMulch_02-gbYbMLm8pnWEMgVxdy.HhJMb4U0R8x_l.jpg - this looks not like Lisp code at all.
15:51:07
pjb
The thing is that things are un flux. There are various user interface toolkits, but they're usually hard to use natively (despite CL libraries). There's CLIM, but AFAIUI, McCLIM is being rewritten.
15:52:25
pjb
And if you wanted to put the GUI on a tablet, then we don't have many CL implementations running there either, and it's awkward.
15:55:50
ym
I'm aware of McCLIM. Don't like it's framework nature, too overthinked protocol. I want just zoom in/out the depth of code represented in network graph in respect to packages/function nesting for example. For me it's most comfortable way of getting a fast glance of system structure.
15:58:25
pjb
If you don't need sophiticated user interaction, people often use secundary programs to render the graph, such as GraphViz, displaying it as a bitmap.
16:02:35
ym
Some good guy from here shared his graph visualization program (cl-frame.lisp). That's enough to start with, but I'm just can't get why such useful features aren't widespread.
16:09:18
pjb
ym: that's because, as I've said, there has been and still is a lot of changes in the graphic and UI technologies.
16:11:51
pjb
Also, you'd have to choose a platform for it. (asuming you cannot write versions for all the platforms). A lot of lispers use macOS. Another big share use linux.
16:12:27
pjb
More of them use emacs. Perhaps this would be the right choice of a platform for such tools.
16:16:56
ym
Well, I don't get this software "evolution" tendency either. I thought that layers of abstraction should hide implementation details and provide simple interface. Like 20 years ago I was able to write SCREEN 12 CRICLE (320, 240), 32 in QBasic to ouput a circle. And now I have to struggle with X protocol, CLX, write over 20 SLOC to make the same.
16:30:13
gendl
Hi, what different conditions or parameter settings can cause (format nil "~t" some-variable) to give different amounts of spacing?
16:31:37
gendl
I think wrapping (with-standard-io-syntax ...) around it will make it work the same in both cases I'm seeing. But without with-standard-io-syntax, the ~t seems to be generating different amounts of whitespace.
16:33:35
pjb
ym: you're right but in the case of UI, there are yearly fads, it's not software, it's fashion.
16:34:40
gendl
phoe: I'll try. I'm just looking at static customer code right now, without the ability to run it in their environment...
16:35:04
pjb
ym: strugglying with X11 would be nothing (and very dated!) Nowadays, you'd have to do this in 3D with OpenGL, etc…
16:37:48
ym
Oh, no. OpenGL is way more horrible thing in this perspective. There is known reason why CS/IT stuff getting worse, but that's off-topic.
16:50:01
gendl
Ok i have an example which shows different output with & without with-standard-io-syntax
16:51:55
gendl
So when I wrap this with w-s-io-s, the output has more whitespace (I can post the actual output if that helps)
16:57:57
phoe
gendl: can you give me the result of (list *print-lines* *print-miser-width* *print-pprint-dispatch* *print-right-margin* *print-level* *print-length* *print-lines* *print-circle* *print-escape* *print-pretty*) ?
16:58:47
pjb
gendl: on the other hand, you have newlines and tabs in your format strings. The newlines are ok but you may prefer explicit ~%. The tabs are bad since they're so implementation dependent.
16:59:42
gendl
looks like *print-pretty* is different, and the *print-pprint-dispatch* is different.
17:00:42
pjb
gendl: In general, I would avoid with-standard-io-syntax. Instead, I would define my own macro setting all the variables as I want them.
17:01:25
gendl
customer is running ANSI mode, I happen to be running modern-mode here (probably bad, I know)
17:03:10
gendl
The customer is comparing output from our previous version which was Allegro CL 9 (32-bit), vs. our new version they're trying to get into production, which is Allegro 10.1 (64-bit).
17:04:16
gendl
phoe: In my function `try' there is a lot of whitespace to the left of all but the first line.
17:04:49
gendl
Should the ~1t force it into column 1, even with all the leading whitespace in the format string?
17:06:26
gendl
But you're right, that doesn't look right. The ======... should obviously be just below the title.
17:07:21
gendl
pjb: It's not a matter of what I want -- this is customer code, i have no control over it. (I can make recommendations to them, though).
17:08:00
phoe
If the behavior of that code changed between different versions of Allegro CL, then I'd ask Franz for clarification.
17:09:36
pjb
gendl: the principle of software is that it should be soft and easily (cheaply) modifiable.
17:10:23
gendl
phoe: Before I go blaming Franz I have to make sure we didn't inadvertently change *print-miser-width* or *print-pretty* in our stuff.
17:10:25
pjb
gendl: otherwise, I would write the code to format tables from raw data and headers, without pre-conceived format. The format would be computed automatically from the data.
17:11:35
pjb
gendl: notice in my example, that you only have 2 formats: ~A for strings, which should not depend on *print- vars, and ~6,3f. If you get your 6 characters, then this format should not depend on the other *print- variables either.
17:12:32
phoe
...and if this is code written by the customer, make a shameless suggestion to them to patch it.
17:16:57
pjb
gendl: since you only have absolute ~T directive, preceded only by literal strings (and absolute ~T directives), (apart for the ~F and ~A that are trivial), then I would say that if you get bad results, it's a bug in the implementation.
17:18:53
gendl
*print-pretty* is supposed to be nil by default, right? I'm noticing in Allegro CL 10.1, *print-pretty* is t, out of the starting gate.
17:19:14
gendl
And the difference between having it t and nil is causing the differences which the customer is reporting.
17:22:25
phoe
The default values for *print-miser-width* and *print-pretty* are implementation-dependent.
17:24:26
gendl
But if you look at the actual documentation for *print-pretty* and *print-miser-width*, they both do say the initial value is implementation-dependent.
17:25:41
trittweiler
there are more instances where that's the case. The initial readtable versus (copy-readtable nil), perhaps. (Haven't checked)
17:26:02
gendl
So 'standard' is what you get with with-standard-io-syntax, but any given vendor can ship an image with non-standard initial values. Got it.
17:46:50
gendl
Disclaimer: it looks like those *print-pretty* and *print-miser-width* might not have changed between Allegro 9 and Allegro 10. I don't want to give wrong information here.
17:47:54
gendl
I have to sort out a few things to confirm (I don't have my Allegro 9 handy here) but it looks like (list *print-pretty* *print-miser-width*) have been (t 40) all along, in Allegro.
19:15:36
pjb
gendl: sorry, :center was wrong. Here's the correction: https://lpaste.net/4162159592878374912