I sure have a bit more problems maintaining Lisp code than writing it. But here I'm more comparing these two endeavors with one another while dealing with Lisp rather than comparing each one to the same endeavor in another language. Writing Lisp code is such a breeze that it is in fact unfair to compare other tasks to it. It's also a bit unfair to compare writing Lisp code to the task of writing code in many other languages.
It is very true that in syntax heavy languages, scanning is made very efficient from the syntax of the code. And sure enough, with big chunks of Lisp code, scanning is a chore. But it is important to understand that scanning is an enabler or, in a more mathematical expression, it is a sufficient condition to make scanning a palatable option. But it is absolutely not a necessary condition.
How?
Lisp code is generally terse and split into several tiny functions. There are some exceptions of course and, based on my experience, there is no exception for such exceptions: they are all tedious to read.
How tiny are the functions you may asked? Here's some stats about my project:
It has 8368 lines of Lisp code for a total of 676 definitions (variables, functions, macros and some other things). The average ratio of lines of code required per definitions is thus 12.37! That is completely, absolutely way way less than code in C, Java or Javascript. You may say that I just have a lot of very tiny utilities in the range of, say, 3 to 5 lines of codes. While it's true in a way, the overall average holds well to about 12 lines of code even if you look at the level of code systems (rather than the whole project) or even at the level of files (rather than whole libraries).
The point that I am trying to get across is that, while I agree there is a connection between having an idea of what the program is doing "at a glance" and gleaning information by scanning thanks to the syntax, this connection is certainly not forwarding any qualitative information about what a program is doing. I mean, from gleaning information from syntax to understand what a code does, nothing is passing that is remotely like 'this does that'. Syntax only guides your eyes. Scanning only allows to locate pieces of interest. But to know what a code does, you have to read it and there is no other way around.
And that's the very purpose of my essay. I am like you. I think I know better what a program is doing when I have some syntax but it's only an illusion. Syntax has absolutely no meaning in itself about what is being done. I have to read the name of the actions and what is passed to them. And if I want to really know what is being done, I have to read it all.
True, it's easier to read code with syntax guiding your eyes but when your code is only 12 lines, you can just read the whole very quickly and you know everything about it, not just the pieces you have gleaned. Syntax heavy languages make it easy to have a lot of information in a short amount of time but they make it more difficult to get the whole picture because they just spread code on so many lines with things less connected than in Lisp (two problems about that: statements do not return results and ask the programmer to do variable plumbing).
At the present time, I think it's all a matter of taste because getting to know what is happening still requires quite some work regardless of the language involved and the more complex what a program should perform, the more code there will be to read.
But Lisp has the edge here I think. Note that some of the various code systems I gave some stats about earlier are not trivial. One has two Lisp code parsers (one of them just gives the stats I exposed, the other one identifies dependencies): 1194 lines for 86 definitions thus a ratio of 13.88. Another one "full view debugs" code: 659 lines for 39 definitions thus a ratio of 16.9.
Despite the goals these code systems tackle, they do not sky-rocket in their stats; every one of them stays very reasonable. And both projects bring much insights about the structure of the code and what is being done. Especially the latter. Full view debugging is about computing all intermediate results inside a given code and layout them all in the browser. It's like when one debugs by hand except that it is all done automatically and everything is here for you to see.
In other words, you can scan and you do not get an idea of what the program is doing. You get what it is really doing. And because Lisp syntax is simple, that full view debugger works on any Lisp code (although of some of the most exotic actions, it does not go into them).
> Syntax only guides your eyes. Scanning only allows to locate pieces of interest. But to know what a code does, you have to read it and there is no other way around.
You could say "paragraphs and punctuation only guide your eyes, but to know what the text says you have to read it, there's no other way around" - ancient greek was written without word spaces, it barely introduces any ambiguity.
> 1194 lines for 86 definitions thus a ratio of 13.88
Just checked my current python codebase. It has 1540 loc, and 95 definitions , for 16.25 on your metric.
And bear in mind you can't put things all one one line in Python (i.e. it would be trivial to write 1 loc per unit in a Lisp, but not good practice). What would it do to your numbers if your program followed SRFI 49? Newline is just a form of punctuation, after all.
Ultimately "no, this language is more awesomer" gets nowhere, I think. You're clearly passionate about Lisp and think it is the best. Good for you. After writing hundreds of thousands of loc in several languages (incl. Lisps), I'm not so sure. Maybe I am just plain wrong. Maybe I just need to do more until I really 'get' it. Who knows!
> You could say "paragraphs and punctuation only guide your eyes, but to know what the text says you have to read it, there's no other way around" - ancient greek was written without word spaces, it barely introduces any ambiguity.
I'm not sure to understand. But I fully endorsed your paragraph statement up to but not beyond the remark that a parenthesis is a punctuation. I was not suggesting we don't need some kind of punctuation or blank lines in code. I was pointing out Lisp dialects are proof you can basically code with just three signs of punctuations: newlines, left parenthesis and right parenthesis.
Are we also clear on the fact every programmer knows how to program in Lisp, even if they didn't even program in it? It's just like function calls, except for the whole language. Really. There's no need to write Lisp code a lot. It is enough to take a few steps back, consider the whole picture and see it for what it is.
Lisp is chainable action perimeters. And that's very easy because it is just like function calls in C, Java, Javascript or many other, more mainstream languages. If you know one of them - and I bet that's the case - then congrats, you can program in Lisp! Whether you choose to do so or not, you're the judge of course and either way is fine with me. But don't say reading or understanding Lisp is hard because for that you only have to learn the vocabulary, as is the case for every programming language.
Anyway, thank you very much for the pointer to SRFI 49! I have searched a bit about indenting Lisp code but never found something that detailed.
I'm sorry for the absurdly fine-grain of my stats. It's just that I have my own Lisp code parser for that and it includes inner comments and blank lines. So it's really that precise but I was silly to recopy these numbers without thinking about the issue.
My point was to say they are consistently that low. And for some languages, it's clearly not the case. But from the few codes of Python I have read and given your own stats, it feels like Python is very consistent. And in my eyes that's definitely a very good thing.
> "Ultimately "no, this language is more awesomer" gets nowhere, I think. You're clearly passionate about Lisp and think it is the best."
I just read again my comment and it can so be read like that... I should have been more careful. I'm truly sorry to have almost versed into a flame debate.
But to read my comment in the direction that Lisp is more awesome or simply the best is to amplify too much my claim which was relative to a precise issue: the needed amount of lines of code against the complexity of the problem. I really said nothing more than Lisp has an edge there and I think the examples give an idea of complex problems: parsing code to get a precise line count or to identify dependencies or to even execute automatically step-by-step the code, these are surely complex tasks. At least it is for me and I can't imagine coding it in other languages than Lisp. Because of their very syntax.
> I was pointing out Lisp dialects are proof you can basically code with just three signs of punctuations: newlines [I think you meant whitespace generally], left parenthesis and right parenthesis.
I agree. In fact, with SRFI49, you can do it with just newlines and spaces. My point is that you can write prose with just spaces, periods and capital letters too (or less). But the use of parentheses, dashes, colons, semicolons, question and exclamation marks, quotation marks, and ellipses, is not a bug. See the metaphor I'm getting at?
> Are we also clear on the fact every programmer knows how to program in Lisp
Yes, if by 'program in Lisp' you mean 'program in a lisp-like syntax'.
I tend to think that syntax is a rather superficial thing, compared to learning the model of computation and the runtime environment. Then Lisp is quite different from C, say. A C programmer doesn't already know Lisp. One problem I had with the OP was that: it seemed to suggest the syntax 'was' Lisp.
I think Python in Lisp syntax would be more Python than Lisp, personally.
Okay, I understand better your point. (I have also misunderstood SRFI49 so it didn't help!). The things you described are features, right?
But what is OP? Opening paragraph?
> compared to learning the model of computation and the runtime environment
There is indeed more important things to learn than syntax. The thing is, for Lisp, chainable action perimeters not only covers the syntax, it also covers the model of computation itself. The basic one at least, without macros and any object system. Still, that basic one is quite broad.
On that question you actually anticipate another article I wanted to share: shortcomings of instructions. It's only logical. If in Lisp dialects the atom is the chainable action perimeter, what other languages have? The answer is the instruction and well, I will keep that for next week but you can read it if you want. The URL is http://www.vagrant-coder.com/articles/english/Shortcomings-o...
Right, they provide additional structure that can in turn help someone express themselves.
But you're right, the complexity can obscure some underlying simplicity.
I suspect that the solution is to disentangle the two: to help programmers understand the computational model independent of the language.
> it also covers the model of computation itself
eval/apply is what I'd consider the model of Lisps, rather than chainable action perimeters. The two are linked, of course, former depending on the latter. I guess you probably mean roughly the same thing by it, so I'm not disagreeing, just saying what I was thinking of.
I agree, the von Neumann model of computation is not necessarily useful if programmers believe it is the only model. But I think it is crucial for programmers to understand.
OP = original post (i.e. the article on your site).
The problem I had with "code is data" or "homoiconicity" is that they didn't really help me to code in Lisp. Although they were obviously big, mouth-watering hints that something is there! :) From an operative point of view, I think "chainable action perimeters" delivers more.
Also, both "code is data" and "homoiconicity" are notions that ends up showing concretely in macros. And the conflict with the notion of "chainable action perimeters" is twofold but always harmful to properly operate as a programmer.
First, we don't deal directly with the true results of macros, which are codes. We let the evaluator compute theses codes internally and it then automatically chains with a call to... itself!
So yes, it can be said one can teach the evaluator new tricks but the infrastructure enabling that and justifying the expressions "code is data" and "homoiconicity" feels a bit too much like a three-card trick to me. The fact what seems the best advice on how to use macros is to not use them when functions would do appears to be, I think, another thumbs-up for the expression "chainable action perimeters".
However, how many different roles do they have apart from writing action perimeters?
The answer is 0!
And 0 times 10, or 100, or 1000 or well, just go for any number, it doesn't matter, that's still 0.
Also, note that Lisp has only parentheses. While in the end, it is a matter of taste, I don't think one can disagree on the fact Lisp only has parentheses and they serve only one purpose.
Other languages have in fact many roles for parentheses while also having brackets and many roles for them while also having curly braces and many roles for them.
An action perimeter returns a value. To perform its work, it needs parameters. That is: values.
Some of these values can be written by hand, others need to be computed. In that latter case, you ask for a computation by writing an action perimeter.
And there's no need for a special syntax to use the value that results in executing that perimeter. You just write it in the appropriate place, as a parameter.
So in practice, you can chain perimeters with one another. Until you have expressed all the computations you wanted the computer to do.
According to google you just made that up? I only see action perimeter in reference to expanding the perimeter of action of the coast guard in Canada. So like... how is an "action perimeter" different than a function? In which case you get the more succinct two words "chainable functions."
After looking at the French version I see that "action perimeter" is from the french perimeter d'action (accents removed) which translates better in english (once again according to the interwebs) as: sphere of operations. http://dictionary.reverso.net/french-english/p%C3%A9rim%C3%A...
Once again, I'd go so far as saying the concept of functions works just as well here, but at least it gets over the near homonym of parameter/perimeter. The chaining of scoped actions is pretty vital to lisp, and I suppose functional programming in general.
I haven't read the notion of action perimeter phrased anywhere else. I just came up with it some years ago when I was trying my colleagues to give Lisp a go.
An action perimeter is different from a function because, for instance, you can write (if <test> <then-clause> <else-clause>).
For a function, all its arguments are evaluated first and then it is applied. That's certainly not the case for if since the whole point of a condition is to refrain from evaluating some code unless a condition is met.
Hence, in Lisp, the simple notation encompasses and is fully operative on every action, including the ones that do not behave like functions. While in many language chaining perimeters is only about function calls. And in addition it is rarely idiomatic to chain function calls in such language.
Thank you for pointing out the similarity between parameter and perimeter which borders on confusion. Thanks to everyone who brought it up to!
It's clear that's an issue I overlooked. The reason is I use the term argument in English and in French, never parameter itself. But that's probably because once I realized the notion of a perimeter is important in Lisp, I stopped using the word 'parameter'.
I'm really sorry to hear my article has wasted your time. You are right, it was rambling. I'm kind of like that and it just surfaces, no matter how hard I try to behave!
Basically, rthomas6 explained it better. But may you allow me to rephrase myself, as a complement as much as an excuse?
There are 3 points.
The first says that Lisp is simple because once you know how to write function calls in classic language (like C, Java, Javascript...), you have all you need to write Lisp code. And really any Lisp code, not just function calls in Lisp.
The second point was that more classic languages go not just one but many different syntax routes while one is good enough to code.
Concretely, for a whole month I was thinking first as writing Java code and then translating it mentally into Lisp. Until I reached enough confidence to let that go and just code in Lisp. When I did that, everything fell apart. Except for one rule: write chainable action perimeters. It is enough, no matter how astonishing it may seem.
The last point was not much about saying that Lisp is beautiful. If anything, I find it elegant but not quite beautiful. No, the last point was about saying it is enough to look at Lisp for 5 minutes and then you are good to go.
Both ways really.
Use it right away, totally possible. Go away from it, entirely reasonable too. Just know that not much other language can maintain such a degree of decency because they generally claim more of your time right at the beginning while also having the nerve to give less.
In short, I'm saying Lisp is nothing special. In particular, it hasn't the ability to illuminate your own programming practice. I'm just saying that from my own particular experience, it does have illuminated my practice because of the other languages.
Lisp has not made me step forward because of what it is in itself. It made me step forward because every other programming languages I practiced have made me walk backwards.
This is so true. I have worked with several legacy code bases and I had discovered that in two opposite settings.
When I was developing on a quite malleable and a bit unpredictable language, I wished it would not be like that.
When I was developing on a less malleable, more predictable one, I was thankful it was like that!
I think it makes sense when you view a program as a cultural artifact. If a programmer has much freedom, so much that he is able to define his own conventions down to how to code the tiniest thing, he should really work hard to pass this "culture".
Unfortunately, as we all know, we seldom have the time and the means to share views about the code. So, indeed, the more universal the idioms, the less we jeopardize the understanding of the code by our peers.
It is very true that in syntax heavy languages, scanning is made very efficient from the syntax of the code. And sure enough, with big chunks of Lisp code, scanning is a chore. But it is important to understand that scanning is an enabler or, in a more mathematical expression, it is a sufficient condition to make scanning a palatable option. But it is absolutely not a necessary condition.
How?
Lisp code is generally terse and split into several tiny functions. There are some exceptions of course and, based on my experience, there is no exception for such exceptions: they are all tedious to read.
How tiny are the functions you may asked? Here's some stats about my project:
It has 8368 lines of Lisp code for a total of 676 definitions (variables, functions, macros and some other things). The average ratio of lines of code required per definitions is thus 12.37! That is completely, absolutely way way less than code in C, Java or Javascript. You may say that I just have a lot of very tiny utilities in the range of, say, 3 to 5 lines of codes. While it's true in a way, the overall average holds well to about 12 lines of code even if you look at the level of code systems (rather than the whole project) or even at the level of files (rather than whole libraries).
The point that I am trying to get across is that, while I agree there is a connection between having an idea of what the program is doing "at a glance" and gleaning information by scanning thanks to the syntax, this connection is certainly not forwarding any qualitative information about what a program is doing. I mean, from gleaning information from syntax to understand what a code does, nothing is passing that is remotely like 'this does that'. Syntax only guides your eyes. Scanning only allows to locate pieces of interest. But to know what a code does, you have to read it and there is no other way around.
And that's the very purpose of my essay. I am like you. I think I know better what a program is doing when I have some syntax but it's only an illusion. Syntax has absolutely no meaning in itself about what is being done. I have to read the name of the actions and what is passed to them. And if I want to really know what is being done, I have to read it all.
True, it's easier to read code with syntax guiding your eyes but when your code is only 12 lines, you can just read the whole very quickly and you know everything about it, not just the pieces you have gleaned. Syntax heavy languages make it easy to have a lot of information in a short amount of time but they make it more difficult to get the whole picture because they just spread code on so many lines with things less connected than in Lisp (two problems about that: statements do not return results and ask the programmer to do variable plumbing).
At the present time, I think it's all a matter of taste because getting to know what is happening still requires quite some work regardless of the language involved and the more complex what a program should perform, the more code there will be to read.
But Lisp has the edge here I think. Note that some of the various code systems I gave some stats about earlier are not trivial. One has two Lisp code parsers (one of them just gives the stats I exposed, the other one identifies dependencies): 1194 lines for 86 definitions thus a ratio of 13.88. Another one "full view debugs" code: 659 lines for 39 definitions thus a ratio of 16.9.
Despite the goals these code systems tackle, they do not sky-rocket in their stats; every one of them stays very reasonable. And both projects bring much insights about the structure of the code and what is being done. Especially the latter. Full view debugging is about computing all intermediate results inside a given code and layout them all in the browser. It's like when one debugs by hand except that it is all done automatically and everything is here for you to see.
In other words, you can scan and you do not get an idea of what the program is doing. You get what it is really doing. And because Lisp syntax is simple, that full view debugger works on any Lisp code (although of some of the most exotic actions, it does not go into them).