8 ms·

Readable Lisp S-expressions Project (2013)

86 points by singularity2001 7y ago

singularity2001 7y ago
How do sweet-expressions differentiate between classical (a b(c d)) and its neoteric reading as (a (b c d)) ? significant space? (a b(c d)) != (a b (c d)) ? That would be acceptable (but break backward-compability?) PS: Thanks for fixing the title but in this case it's much less expressive than the original.
- dang 7y ago
  The submitted title was "readable lisp with infix and less ((braces))". That was not the original. The original title is "Readable Lisp S-expressions Project", so a moderator changed it to that, in accordance with this site guideline: "Please use the original title, unless it is misleading or linkbait." On HN, being the submitter of an article conveys no special rights over the content, such as how to frame it for readers. If you want to express your opinion, the place for that is in a comment; then your view is the same level as other users'. Titles are by far the biggest influence on threads, so this rule is a big deal. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
singularity2001 7y ago
Summary: Readable is a lisp plugin which allows you to drop superfluous braces and use function and infix notation: (define (factorial n) (if (<= n 1) 1 (* n (factorial (- n 1))))) can now be written as define factorial(n) if {n <= 1} 1 {n * factorial{n - 1}} One more proof that the original lisp is a god like language. And now even beautiful to look at.
- AlexanderDhoore 7y ago
  "a god like language" Such hyperbole can only be found in the lisp world. You guys need to take lisp off its pedestal.
  - delish 7y ago
    > Such hyperbole can only be found in the lisp world. Paul Graham may agree with you! Graham found a guy on slashdot with the same funny notion: > "I have heard more than one LISP advocate state such subjective comments as, "LISP is the most powerful and elegant programming language in the world" and expect such comments to be taken as objective truth. I have never heard a Java, C++, C, Perl, or Python advocate make the same claim about their own language of choice." > - A guy on Slashdot. What theory fits this data? http://www.paulgraham.com/quotes.html http://www.paulgraham.com/quotes.html
    - AlexanderDhoore 7y ago
      Any idea what he means with "What theory fits this data" ?
      - singularity2001 7y ago
        He is (hyperbolically?) asking for a scientific explanation `why` Lispers are so convinced of their language (and others not).
  - CDSlice 7y ago
    I don't know, some Rust devs seem to think that too. That's why the Rust Evangelism Strike Force exists.
  - lispm 7y ago
    maybe it was irony? or something similar?
  - krapp 7y ago
    The one that always gets me is "Lisp has no syntax."
neilv 7y ago
There've been so many attempts at removing the parentheses from Lisp, to make it look more like C/C++/Java, or (more recently) Python, or other. FWIW, there've been many attempts in Scheme (and Racket), including one by the core Racket developers (Honu [1]), but they've never taken off. New people decide to use parentheses. There's a phenomenon with Lisps, in which, speaking loosely, half the people who first see a Lisp think the parentheses are a problem, and immediately start to propose "solutions" for "acceptance". But then they try the Lisp with the parentheses, in an editor with at least simple indenting support, and they very quickly get used to it, and maybe even value it. (A small percentage of them will still put each close-paren on its own line, for a substantially longer period, but it seems even most of them will quickly learn to snuggle close-parens and possibly to use fancier editor commands for movement and editing based on expressions rather than lines.) Programmers seem more malleable than we might think. I'm not as sure about those mathematicians or scientists who try to minimize their time learning programming, or who are necessarily working with hairy expressions in LaTeX and don't want to have to keep translating. For possible use of those people, there are a number of efforts to permit expressions to be in more familiar infix order [2], and to support familiar TeX math notation in the Racket-based typesetting/documentation system [3]. (And if you don't like those, Racket will let programmers plug in your own reader or `#lang` to make another attempt at this atop Scheme.) [1] https://docs.racket-lang.org/honu/Examples.html https://docs.racket-lang.org/honu/Examples.html [2] https://docs.racket-lang.org/guide/hash-reader.html#(part._readtable) https://docs.racket-lang.org/guide/hash-reader.html#(part._r... [3] https://docs.racket-lang.org/scribble-math/index.html https://docs.racket-lang.org/scribble-math/index.html
- singularity2001 7y ago
  >> There've been so many attempts at removing the parentheses from Lisp, to make it look more like C... I think it's less about looking like C (or other) it's about looking like normal Math: (f 1) vs f(1). The above plugin solves this. Maybe the neoteric feature is the most important of the three extensions. But then again `unnecessary` braces are nothing to torture malleable newcomers with, they are just a thing to get rid of.
  - 7y ago
bitwize 7y ago
Lisp, as McCarthy proposed it in 1958, actually had an alternate syntax called M-expressions that would be perfectly readable to any JavaScript programmer: (foo a b) became foo[a,b]. It never took off. From the earliest days -- before video terminals were a thing, let alone video-terminal editors that could match parens and indent automatically -- people just preferred working with sexprs. I think it has to do with the fact that while mexprs are easier to read with prior ALGOL experience, sexprs are easier to transform, and to reason about their transformation. I think Lisp is one of those things where, you either get it or you don't, and once you do get it parens are a non-issue. There's a fundamental leap of insight that requires enormous activation energy to achieve.
- TylerE 7y ago
  Elixir is pretty close to readable lists. Even with macros and everything.
  - bodi 7y ago
    Frankly Ill take the extra visual structure of square brackets and commas for lists instead of overloaded parens and white spaces of Lispy sexprs any day.
- ddragon 7y ago
  The idea of the m-expressions might be coming back though, two of the popular newcomers are homoiconic languages (depending on your definition), Elixir as a functional programming language and Julia as an imperative CLOS inspired language. Being not as powerful (able to create any valid syntax due to more complex and rigid parsing rules) and trivial to manipulate code as data as s-expression is considered a feature, as it helps preventing the proliferation of language extensions while still allowing them when their benefits outweighs the costs. Even the main elixir metaprogramming book starts with saying: "the first rule of macros: don't use macros", and in Julia you have to attach a @ to call a macro to make it clear that the normal rules of the language do not apply ahead. Those languages also focus in providing everything the user needs without the use of macros, which are for more advanced purposes. While people who use Lisp eventually see the advantages of s-expressions (or at least of writing more idiomatic code in those languages), being attractive to new users coming from the more popular languages is very important (and like clojure interoperate with java, it might be even easier to make a lisp that has perfect interoperability with Elixir for example, so both groups can coexist).
beders 7y ago
I've made clojure my main language late last year and while reading lisp code seemed alien at first, I've now adapted and have no trouble reading s-expressions. And once you truly understand that `(map inc [1 2 3 4])` is just a list, things like macros begin to click and you understand the power that is given to you. In fact, I'm missing an equivalent to paredit now when I have to go back and code Java/JavaScript :)
dreamcompiler 7y ago
There's a line in The Matrix where Neo asks Cypher why he looks at the raw green code of the Matrix. He replies "You have to...and all I see is blonde, brunette, redhead" (or something to that effect). Every time somebody proposes to "fix" Lisp's syntax it reminds me of that scene. It sounds like a newbie Lisp programmer who hasn't yet experienced the thrill of seeing beyond the parentheses. And the mind-boggling compositional utility that comes from leaving them alone.
- singularity2001 7y ago
  The point is: Most of the parentheses are superfluous and removing them (in the right way) takes nothing away from the mind-boggling compositional utility.
  - dreamcompiler 7y ago
    Parens are anything but superfluous. Substituting whitespace for parens is a net loss IMO because indentation errors become semantic rather than merely unaesthetic. And elegant composition is impossible with infix notation unless -- you add parens again.
    - traderjane 7y ago
      Does the Python community struggle with indentation? I thought it was largely a non-issue.
      - singularity2001 7y ago
        Indentation is an occasional minor annoyance when copy pasting, but otherwise mostly solved by IDEs. In any case very acceptable given the much increased readability and esthetics. I'm not sure if semantic bugs from mixing tabs and spaces are even possible with modern python parsers. if 1: <tab>if 0: <tab><tab>print(1) <spaces*n>print(2) could print 2 if mixing tabs and spaces were allowed. was it ever?
      - thechao 7y ago
foobar_ 7y ago
I like begin and end instead of the parens. Allman style ftw!. I've been thinking of something along the lines of an xml based notation for lisp. It's a shame lisp doesn't allow a simple text-based preprocessor.
- singularity2001 7y ago
  text-based preprocessor. Maybe 'asdf'? IDK, that's what this plugin uses: (require "asdf") (asdf:load-system :readable) (readable:enable-sweet) ...
- andyjpb 7y ago
  Something similar to sxml? https://en.wikipedia.org/wiki/SXML https://en.wikipedia.org/wiki/SXML XML has attributes which S-exprs don't. This can be solved by convention (as SXML does) and doesn't really represent a difference in expressibility. S-exprs have quote and unquote which XML doesn't. This is a fundamental difference and makes it hard to convert Lisp code that mixes code and data representations.
yason 7y ago
Each time as fun. If you know Lisp you will instinctively convert any syntax back to S-expressions anyway because that's how things will eventually work anyway and because you can't think of Lisp macros otherwise. So, the syntax becomes a burden, and thus you settle for the minimalist, easiest way to denote trees. Parentheses.
deleted 7y ago
[deleted]
- deleted 7y ago
  [deleted]
  - deleted 7y ago
    [deleted]
gumby 7y ago
Trying to fix a problem that doesn't exist.
goto11 7y ago
The parentheses in Lisp are like the white-space in Python - something non-users often get hung-up about when looking at the language, but which turns out to be a non-issue when using the language for a short while. A more conventional syntax might look more appealing for non-Lispers, but I don't think it will make a big difference for adoption. If you want a more conventional-looking language, there are already plenty to choose from.
elderK 7y ago
I've read many of the comments. Lots of talk about removing the parenthesis, using things like Tree-Notation and such. Really, all I can say is that you can pry the parens from my cold, dead, cantankerous hands. :P Maybe it's because I've been playing with Lisp, in one form or another, on and off for several years. But I never found the parens really all that bad. It's no problem at all as long as you have basic paren matching support in whatever editor you use. And if you happen to use an editor that supports the structured manipulation of S-expressions, well, it's a pretty neat experience. I think the only time the parens bother me is if I print source code out. But even then, there are clear conventions on how Lisp source should be laid out and indented, so you adapt pretty quick, even in the "worst case." shrug

singularity2001 7y ago

How do sweet-expressions differentiate between classical (a b(c d)) and its neoteric reading as (a (b c d)) ? significant space? (a b(c d)) != (a b (c d)) ? That would be acceptable (but break backward-compability?) PS: Thanks for fixing the title but in this case it's much less expressive than the original.

dang 7y ago
The submitted title was "readable lisp with infix and less ((braces))". That was not the original. The original title is "Readable Lisp S-expressions Project", so a moderator changed it to that, in accordance with this site guideline: "Please use the original title, unless it is misleading or linkbait." On HN, being the submitter of an article conveys no special rights over the content, such as how to frame it for readers. If you want to express your opinion, the place for that is in a comment; then your view is the same level as other users'. Titles are by far the biggest influence on threads, so this rule is a big deal. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

singularity2001 7y ago

Summary: Readable is a lisp plugin which allows you to drop superfluous braces and use function and infix notation: (define (factorial n) (if (<= n 1) 1 (* n (factorial (- n 1))))) can now be written as define factorial(n) if {n <= 1} 1 {n * factorial{n - 1}} One more proof that the original lisp is a god like language. And now even beautiful to look at.

AlexanderDhoore 7y ago
"a god like language" Such hyperbole can only be found in the lisp world. You guys need to take lisp off its pedestal.
- delish 7y ago
  > Such hyperbole can only be found in the lisp world. Paul Graham may agree with you! Graham found a guy on slashdot with the same funny notion: > "I have heard more than one LISP advocate state such subjective comments as, "LISP is the most powerful and elegant programming language in the world" and expect such comments to be taken as objective truth. I have never heard a Java, C++, C, Perl, or Python advocate make the same claim about their own language of choice." > - A guy on Slashdot. What theory fits this data? http://www.paulgraham.com/quotes.html http://www.paulgraham.com/quotes.html
  - AlexanderDhoore 7y ago
    Any idea what he means with "What theory fits this data" ?
    - singularity2001 7y ago
      He is (hyperbolically?) asking for a scientific explanation `why` Lispers are so convinced of their language (and others not).
- CDSlice 7y ago
  I don't know, some Rust devs seem to think that too. That's why the Rust Evangelism Strike Force exists.
- lispm 7y ago
  maybe it was irony? or something similar?
- krapp 7y ago
  The one that always gets me is "Lisp has no syntax."

neilv 7y ago

There've been so many attempts at removing the parentheses from Lisp, to make it look more like C/C++/Java, or (more recently) Python, or other. FWIW, there've been many attempts in Scheme (and Racket), including one by the core Racket developers (Honu [1]), but they've never taken off. New people decide to use parentheses. There's a phenomenon with Lisps, in which, speaking loosely, half the people who first see a Lisp think the parentheses are a problem, and immediately start to propose "solutions" for "acceptance". But then they try the Lisp with the parentheses, in an editor with at least simple indenting support, and they very quickly get used to it, and maybe even value it. (A small percentage of them will still put each close-paren on its own line, for a substantially longer period, but it seems even most of them will quickly learn to snuggle close-parens and possibly to use fancier editor commands for movement and editing based on expressions rather than lines.) Programmers seem more malleable than we might think. I'm not as sure about those mathematicians or scientists who try to minimize their time learning programming, or who are necessarily working with hairy expressions in LaTeX and don't want to have to keep translating. For possible use of those people, there are a number of efforts to permit expressions to be in more familiar infix order [2], and to support familiar TeX math notation in the Racket-based typesetting/documentation system [3]. (And if you don't like those, Racket will let programmers plug in your own reader or `#lang` to make another attempt at this atop Scheme.) [1] https://docs.racket-lang.org/honu/Examples.html https://docs.racket-lang.org/honu/Examples.html [2] https://docs.racket-lang.org/guide/hash-reader.html#(part._readtable) https://docs.racket-lang.org/guide/hash-reader.html#(part._r... [3] https://docs.racket-lang.org/scribble-math/index.html https://docs.racket-lang.org/scribble-math/index.html

singularity2001 7y ago
>> There've been so many attempts at removing the parentheses from Lisp, to make it look more like C... I think it's less about looking like C (or other) it's about looking like normal Math: (f 1) vs f(1). The above plugin solves this. Maybe the neoteric feature is the most important of the three extensions. But then again `unnecessary` braces are nothing to torture malleable newcomers with, they are just a thing to get rid of.
- 7y ago

bitwize 7y ago

Lisp, as McCarthy proposed it in 1958, actually had an alternate syntax called M-expressions that would be perfectly readable to any JavaScript programmer: (foo a b) became foo[a,b]. It never took off. From the earliest days -- before video terminals were a thing, let alone video-terminal editors that could match parens and indent automatically -- people just preferred working with sexprs. I think it has to do with the fact that while mexprs are easier to read with prior ALGOL experience, sexprs are easier to transform, and to reason about their transformation. I think Lisp is one of those things where, you either get it or you don't, and once you do get it parens are a non-issue. There's a fundamental leap of insight that requires enormous activation energy to achieve.

TylerE 7y ago
Elixir is pretty close to readable lists. Even with macros and everything.
- bodi 7y ago
  Frankly Ill take the extra visual structure of square brackets and commas for lists instead of overloaded parens and white spaces of Lispy sexprs any day.
ddragon 7y ago
The idea of the m-expressions might be coming back though, two of the popular newcomers are homoiconic languages (depending on your definition), Elixir as a functional programming language and Julia as an imperative CLOS inspired language. Being not as powerful (able to create any valid syntax due to more complex and rigid parsing rules) and trivial to manipulate code as data as s-expression is considered a feature, as it helps preventing the proliferation of language extensions while still allowing them when their benefits outweighs the costs. Even the main elixir metaprogramming book starts with saying: "the first rule of macros: don't use macros", and in Julia you have to attach a @ to call a macro to make it clear that the normal rules of the language do not apply ahead. Those languages also focus in providing everything the user needs without the use of macros, which are for more advanced purposes. While people who use Lisp eventually see the advantages of s-expressions (or at least of writing more idiomatic code in those languages), being attractive to new users coming from the more popular languages is very important (and like clojure interoperate with java, it might be even easier to make a lisp that has perfect interoperability with Elixir for example, so both groups can coexist).

beders 7y ago

I've made clojure my main language late last year and while reading lisp code seemed alien at first, I've now adapted and have no trouble reading s-expressions. And once you truly understand that `(map inc [1 2 3 4])` is just a list, things like macros begin to click and you understand the power that is given to you. In fact, I'm missing an equivalent to paredit now when I have to go back and code Java/JavaScript :)

dreamcompiler 7y ago

There's a line in The Matrix where Neo asks Cypher why he looks at the raw green code of the Matrix. He replies "You have to...and all I see is blonde, brunette, redhead" (or something to that effect). Every time somebody proposes to "fix" Lisp's syntax it reminds me of that scene. It sounds like a newbie Lisp programmer who hasn't yet experienced the thrill of seeing beyond the parentheses. And the mind-boggling compositional utility that comes from leaving them alone.

singularity2001 7y ago
The point is: Most of the parentheses are superfluous and removing them (in the right way) takes nothing away from the mind-boggling compositional utility.
- dreamcompiler 7y ago
  Parens are anything but superfluous. Substituting whitespace for parens is a net loss IMO because indentation errors become semantic rather than merely unaesthetic. And elegant composition is impossible with infix notation unless -- you add parens again.
  - traderjane 7y ago
    Does the Python community struggle with indentation? I thought it was largely a non-issue.
    - singularity2001 7y ago
      Indentation is an occasional minor annoyance when copy pasting, but otherwise mostly solved by IDEs. In any case very acceptable given the much increased readability and esthetics. I'm not sure if semantic bugs from mixing tabs and spaces are even possible with modern python parsers. if 1: <tab>if 0: <tab><tab>print(1) <spaces*n>print(2) could print 2 if mixing tabs and spaces were allowed. was it ever?
    - thechao 7y ago

foobar_ 7y ago

I like begin and end instead of the parens. Allman style ftw!. I've been thinking of something along the lines of an xml based notation for lisp. It's a shame lisp doesn't allow a simple text-based preprocessor.

singularity2001 7y ago
text-based preprocessor. Maybe 'asdf'? IDK, that's what this plugin uses: (require "asdf") (asdf:load-system :readable) (readable:enable-sweet) ...
andyjpb 7y ago
Something similar to sxml? https://en.wikipedia.org/wiki/SXML https://en.wikipedia.org/wiki/SXML XML has attributes which S-exprs don't. This can be solved by convention (as SXML does) and doesn't really represent a difference in expressibility. S-exprs have quote and unquote which XML doesn't. This is a fundamental difference and makes it hard to convert Lisp code that mixes code and data representations.

yason 7y ago

Each time as fun. If you know Lisp you will instinctively convert any syntax back to S-expressions anyway because that's how things will eventually work anyway and because you can't think of Lisp macros otherwise. So, the syntax becomes a burden, and thus you settle for the minimalist, easiest way to denote trees. Parentheses.

deleted 7y ago

[deleted]

deleted 7y ago
[deleted]
- deleted 7y ago
  [deleted]

gumby 7y ago

Trying to fix a problem that doesn't exist.

goto11 7y ago

The parentheses in Lisp are like the white-space in Python - something non-users often get hung-up about when looking at the language, but which turns out to be a non-issue when using the language for a short while. A more conventional syntax might look more appealing for non-Lispers, but I don't think it will make a big difference for adoption. If you want a more conventional-looking language, there are already plenty to choose from.

elderK 7y ago

I've read many of the comments. Lots of talk about removing the parenthesis, using things like Tree-Notation and such. Really, all I can say is that you can pry the parens from my cold, dead, cantankerous hands. :P Maybe it's because I've been playing with Lisp, in one form or another, on and off for several years. But I never found the parens really all that bad. It's no problem at all as long as you have basic paren matching support in whatever editor you use. And if you happen to use an editor that supports the structured manipulation of S-expressions, well, it's a pretty neat experience. I think the only time the parens bother me is if I print source code out. But even then, there are clear conventions on how Lisp source should be laid out and indented, so you adapt pretty quick, even in the "worst case." shrug