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5:25:04
vtomole
drmeister: I'm trying to implement a lisp intepreter in C, and i'm having a bit of trouble writing the parser. Do I need to implement a function that puts linked lists inside linked lists?
5:28:03
iqubic
Does C have support for heterogeneous data structures? I ask because lisp is basically just one giant heterogeneous data structure.
5:31:25
pjb
drmeister: well, the critical section is the updating of the dispatching functions of the generic functions. This is the only place where you should need mutexes, when you update the generic functions (ie. when classes or methods are changed).
5:33:06
pjb
vtomole: start by writing your interpreter in lisp, it'll be easier. Then you may write a translator for the subset of lisp you used to implement your lisp interpreter in lisp, to translate it to C…
5:35:15
vtomole
I did. I then had to implement cons() in C and I don't think I did it right cause my recursion parsing is not working correctly.
5:35:46
pjb
vtomole: I fail to see the link between implementing cons and implementing a recursive parser.
5:37:12
iqubic
pjb: I think the issue is knowing where the closing bracket of the cdr of a particular cons cell is.
5:38:07
vtomole
Using this as a reference worked for me in Lisp. C is a different animal: http://norvig.com/lispy.html
5:38:23
vtomole
From that page :def read_from_tokens(tokens): "Read an expression from a sequence of tokens." if len(tokens) == 0: raise SyntaxError('unexpected EOF while reading') token = tokens.pop(0) if '(' == token: L = [] while tokens[0] != ')': L.append(read_from_tokens(tokens)) tokens.pop(0) # pop off ')' return L elif ')' == token: raise SyntaxError('unexpected )')
5:38:52
iqubic
In order to parse lisp I would first create an ast of the code, then interpret that ast.
5:39:10
pjb
Perhaps you should read: Lisp in Small Pieces http://pagesperso-systeme.lip6.fr/Christian.Queinnec/WWW/LiSP.html http://pagesperso-systeme.lip6.fr/Christian.Queinnec/Books/LiSP-2ndEdition-2006Dec11.tgz
5:40:42
pjb
And given that lisp objects such as cons cells are such a fundamental and basic layer, it should have been developed and tested heavily long berfore you started writing the parser!
5:41:31
iqubic
I'm not sure I see the issue. Can you share your code with use so that we might help you?
5:42:44
vtomole
I'm basically trying to translate this to C: http://paste.lisp.org/display/356603. Let me organize my code first before I post.
5:44:42
stylewarning
Does anyone have a fix for: Warning (slime): Caught error during fontification while searching for forms that are suppressed by reader-conditionals. The error was: (args-out-of-range "" 0).
6:20:56
vtomole
I'm basically trying to put a linked list inside of a linked list((cons (token, read_from_tokens(cdr(token_list))));, but i'm running into an infinite loop:http://paste.lisp.org/display/356606
6:23:52
iqubic
But yeah, a union is better for that than a pair of strings. What would happen if the strings got mismatched?
6:25:29
iqubic
And a pair of strings is a bad way to store anything. A union is a way better way to do that.
6:26:46
|3b|
ACTION assumes union would be to add tagging, and would store struct cons and anything else
6:27:48
|3b|
other option would be to play tricks with pointers like most native implementations do, but i'd probably avoid that without a lot of knowledge of C spec to avoid undefined behavior, and implementation details
6:28:10
vtomole
Yeah I did that earlier, but that would mean I need to keep track of types so that I can dereference them when I need the value.
6:38:11
beach
I would use a struct for each kind of object and a void* for a field that should contain some other object. And you need to include the type somehow so that you can figure that out at run-time.
6:53:23
|3b|
you would either put the type in all of the structs, use a union to associate the type with all structs
7:51:50
guicho
I don't usually come here unless I beg your collective knowledge. so as expected, I have a question.
7:52:24
guicho
I forgot the name of a cl project for matrix operations. it was on github. the readme stated that one of its main difference from the other libraries is that it overrides the standard operator such as *, + as a CLOS method. Could you identify this library?
7:59:15
guicho
https://gist.github.com/guicho271828/23e5d474adcd9890b9d41b622f458644 these are not what Im looking for
8:34:59
guicho
I hope this is not the case that I literally *dreamed* this library ... and remembering this as if I actually saw it...
11:37:25
edgar-rft
guicho, cl-ana provides its own versions of the basic math functions CL gives you but with the ability to extend them for whatever types you want: <https://github.com/ghollisjr/cl-ana>
11:52:15
whoman
subconsciously thinking, "CL could have already had ability to extend basic math funs if it were golden idea"
11:54:57
edgar-rft
I think the main problem here is that number-crunching needs all speed you can get out of any programming language. A full generic dispatch on every basic math function is way too slow for that.
12:26:40
guicho
edgar-rft, wow, thank you that. yes this is what I was looking for. so this is why keywords like "matrix" nor "array" didn't work.
13:02:50
edgar-rft
guicho, I knew I had read that somewhere, but same problem like you, the internet is way too big and Google is way too ignorant about Lisp.
13:05:12
Josh_2
Most people are ignorant about Lisp. Peoples reaction when I say I like CL the most is normally some form of "ermagurd how could you?"
13:10:41
edgar-rft
Josh_2: that's good because it means you only need some mediocre Lisp knowledge to beat them all
13:16:43
dim
I have the good luck to learn lisp at school, in between C++ and Java. Unfortunately the teacher was so ignorant about it that we only played with cons, car and cdr and we had to answer cryptic exercises of no value. I guess the whole class was disgusted and saw no point in Lisp at all.
13:17:12
p_l
dim: that's common case in the vestigal courses that introduce various forms of programming
13:17:55
p_l
dim: in my case, I believe we had a bit of Prolog instead, don't recall if we had lisp directly, but we had a lisp-derived language (Jess) much later on
13:19:31
dim
Java has ABCL and Kawa too, and Clojure nowadays, if you depend on the JVM to run programs... but anyway
13:40:36
p_l
dim: Clojure is the only one that is widely known unless someone takes special effort to find
13:54:50
Baggers
ACTION googles lisp. lisp the lang beats lisp the condition, then its common-lisp.net then it's gigamonkeys
13:55:53
dim
you know that your google results depend on your habits and who you are seen from Google, right? e.g. if I search for “postmodern” the first result I have is the PostgreSQL driver for Common Lisp…
13:56:29
Baggers
did it from safari without being logged into anything. guess they are basing on ip then
13:58:22
edgar-rft
Search engines are not "intelligent" by default. If nearly nobody searches for Lisp stuff, Google can't know. Just as simple as that.
13:58:49
Baggers
fwiw got the same on chrome that I just ran for the first time on a phone i've just flashed in icognito mode and on 4g
13:59:14
dim
https://arstechnica.com/information-technology/2017/02/now-sites-can-fingerprint-you-online-even-when-you-use-multiple-browsers/
14:05:30
Baggers
ACTION would love to know what someone using some anonymizer/vpn/etc gets for googling lisp.
15:53:48
phoe_
where the library seemingly expects B G R A as it reads these values not as four (unsigned-byte 8)s but rather as one (unsigned-byte 32) which of course is little-endian
15:59:35
phoe_
edgar-rft: I'm passing a whole vector to Qtools's QImage to be displayed, so this doesn't help me.
16:06:26
pjb
phoe_: (loop for i :below (length v) :by 4 :do (rotatef (aref v i) (aref v (+ i 3))) (rotatef (aref v (+ i 1)) (aref v (+ i 2))))
16:13:06
pjb
phoe_: but the point is that when you have vector with O(1) access, you can loop with any O(1) number of variables by indexing the vector!
16:23:56
pjb
phoe_: now, of course, the right answer would be to update your functional asbtractions: (defun red (pixmap index) (aref pixmap (+ 2 index))) instead of (defun red (pixmap index) (aref pixmap (+ 1 index))) etc.
16:24:29
pjb
newcoder: writing the first version of a program that the programmer things will never be used by users, but that the manager has already sold and will distribute world wide.
16:27:10
pjb
The wrong way is to implement a user interface, to have a feel of how it will look, but not the internals. This is wrong, because then you will spend 2 years hearing why doesn't it work, since the UI is already done!
16:27:44
pjb
The okay way is to implement the core functionality/algorithm, and to stick a CLI on it, to validate the "MVP".
16:29:45
pjb
The advantage of CLI nowadays, is that no user expect to have to use it. So you can demonstrate the feature: look, I enter this data, I get this result, without the user expecting to have a finished product.
16:32:27
Josh_2
I'm not a very skilled Lisper but I can write programs much faster in Lisp than I can in C++
16:44:46
mr_yogurt
Are there any big utility libraries (maybe something like boost, although not exactly boost since a lot of it is unnecessary for CL) for common lisp?