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My goal from the beginning was to continue where JMC left off: to continue building Lisp up from axioms till I have a more complete language. I've compromised a bit to make it something runnable, which I think you need in order to test out your ideas on programs of substantial length. But "practical programming" is not in itself the main goal.

Paradoxical as it sounds, that may be the way to end up with the best language for practical programming. It worked for McCarthy, and I think there's more juice yet to be squeezed out of this orange.

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Wasn't McCarthy working on a model that's more elegant than Turing machines?

As far as axioms go, you can't get simpler than the Turing machine: it doesn't even have a notion of a variable, let alone types or strings.

I don't know about the history of Lisp other from what I've read from you, but it seems what McCarthy was working on was a more elegant model, rather than an "axiomatically pure" model.

Arc on the other hand, is trying to compete with Ruby and Python.

Lambda calculus is actually simpler than Turing machines. There are only two primitives: function definition and application. You can use that to express any computable function, including booleans, conditionals, integers, arithmetic, strings, etc.

I believe his goal was a formal model of computation that was also good for expressing algorithms. Plus eval probably seemed like a neat trick. We take it for granted, but imagine how pleasing that must have been to think of.

I'm not trying to compete with Ruby and Python. If I were I'd be recruiting armies of people to write libraries.

I meant "compete" in terms of expressiveness. And actually that's not the only thing.

A language that can express algorithms in few lines that are very cryptic (read: hard to read) is not very useful.

I think were python hit the mark spot on is the adoption of the idea that "programs should be written for people to read, and only incidentally for machines to execute".

And where ruby hit it spot on is "optimizing for happiness", I particularly like Matz's his idea about "harmony"[1].

  Matz> I believe consistency and orthogonality are tools of design, not the primary goal in design.

If the language forces you to carry the compiler in your brain as you try to read code, it's a bad idea.

One of the things that annoy me about lisp as a beginner, and maybe this only because I'm a beginner, is that I always have to manually compile code into the syntax tree.

[1]: http://www.artima.com/intv/ruby2.html

A language that can express algorithms in few lines that are very cryptic (read: hard to read) is not very useful.

Part of Arc's design philosophy is to never inconvenience advanced users in order to serve novice ones. Long, descriptive names help people unfamiliar with a language's operators better understand what they do, but the length can become a burden once they do know.

For example, when I first started learning Arc, it would have saved me some headache if afn had been named anaphoric-function. Now I would find that a real nuisance. I love being able to invoke such a powerful abstraction with just three keystrokes.

Here's an interesting exercise. This is the given solution to the Arc Challenge [1]:

  (defop said req
    (aform [w/link (pr "you said: " (arg _ "foo"))
             (pr "click here")]
      (input "foo")
      (submit)))

What would you prefer that it looked like? If you replaced all the abbreviated names with long descriptive ones, you'd have something like:

  (define-operator said request
    (html-anaphoric-form
      [html-with-link 
        (print "you said: " (argument _ "foo"))
        (print "click here")]
      (html-input "foo")
      (html-submit)))

---

[1] http://arclanguage.org/item?id=722

I despite long names in JavaLibrariesAndFrameWorks but I don't appreciate tla aop (three letter acronyms all over the place).

Your second code snippet is actually much more pleasant to read.

Sure, it's subjective. :)

I forgot to mention though that the idea is to use the shortest names possible for the core language operators. That's when they're the biggest win, since you'll learn those well enough not to need descriptive names, and they cut program length more substantially since they're used so often.

Right, and I agree with that. I prefer = over define.

The problem comes when everything is "inlined".

    (def color (r g b)
      (with (c (table) 
             f (fn (x) (if (< x 0) 0 (> x 255) 255 x)))
        (= (c 'r) (f r) (c 'g) (f g) (c 'b) (f b))
        c))

This is the first thing in html.arc

I can't make sense of it, it's way too terse.

This is probably why python doesn't have a proper lambda expression.

EDIT:

After some pondering, I see what it does ..

An equally terse implementation in python:

  def limit(n, lower, upper):
      if n < lower: return lower
      if n > upper: return upper
      return n

  def color(*args):
      return dict(zip("rgb", [limit(c, 0, 255) for c in args]))

  >>> color(10, 20, 30)
  {'r': 10, 'b': 30, 'g': 20}

This is a lot clearer, without sacrificing conciseness:

  def color(*args):
      rgb_values = [limit(c, 0, 255) for c in args]
      return dict(zip("rgb", rgb_values))

By simply getting the inlined list comprehension outside the dict expression, the whole thing becomes 10 times easier to read: "Ah, it's mapping 'rgb' characters to rgb values."

"Axioms" has a nice, mathy ring of solidity to it, but I'm pretty sure that, along with the axioms you are analyzing there are others you are barely thinking about but which also form the foundation of Arc. For example, the notion of code and data being the same in Lisp: strings of text. Is that an axiom? That's certainly one of the keys to the unusual power and flexibility of Lisp. Yet text data these days is a very rich construct. A typical string might be an entry in a Thai-Japanese dictionary. To accommodate general text data for the next hundred years, you must use Unicode (axiomatic, whether you realize it or not), which implies that the code itself (being data) must be in Unicode, which has implications for the semantics of code and how you walk through a string-as-list "character by character". Are you planning to have macros? Of course you are, which means that macros will be designed based on the assumption that what they parse is Unicode. What implications does that assumption have for the design of macro syntax? I don't know, but if you start by designing macros on the basis of ASCII assumptions, your macros will become a mess when you eventually try to retrofit Unicode. Most languages don't have to deal with this, because code and data are assumed separate.

I don't know how Lisp-style strings-as-lists should be designed when the strings are Unicode, and how, therefore, macros should be designed, but it seems pretty darned fundamental, not something to tack on later. And this is just the first example that comes to mind. Fundamental decisions have implications for ease of learning the language, ease of evolving code, for performance, for ability to run in parallel, for difficulty of implementation, for portability, for security, and for so many issues that I'm not even aware of, all of which have implications for one another.

No group of half-dozen friends, no matter how smart, knows enough to get these axioms right. Too many lessons have been learned by the rest of the world to ignore what they've found and hope to do well by reasoning from some incomplete set of first principles.

Of course, if you're just trying to solve a fun math problem by eliminating the parts of the real world you don't feel like thinking about, then fine. Those of us who need real tools will look elsewhere. You can publish the solution to your math puzzle. You may just not have the time or inclination to do more, and who could blame you? You're obviously very busy. But if it is intended as a tool for real programming, then carefully designing only the parts you care about will produce yet another mess of poorly integrated retrofits and kludges as the lessons long learned by the rest of the world (post-McCarthy) are belatedly rediscovered. Without project management that includes leveraging the expertise of a large community, Arc probably won't be usable as anything more than a source of ideas for the real 100-year language.

What you talk about regarding unicode for example is just an implementation detail. Unicode strings fundamentally are a list of unicode code points.

UTF-8 is just one of the possible encodings of such list. It can be decoded and converted to UTF-32 before it goes to the reader/lexer.

No, it's not "just an implementation detail". I don't want to get into the details here, but your assumption that having your strings in one encoding composed conceptually of code points in a different encoding is not necessarily the way to go. I was on a JCP expert committee that rejected that option for Java, but that doesn't mean it couldn't end up best for Arc. It's just not as easy a decision as you imply. There are alternative approaches with different pros and cons, and since these abstractions all leak, you need to make a cross-implementation decision so that you don't end up with different coding practices on different platforms. Plus all the other issues that Unicode presents that make parsing a challenge that might have implications for a language that is famous for parsing and rewriting its own source at runtime.... These could all be worked out through a vigorous discussion process among a diverse group large enough to make sure that the implications of each approach are understood, but Graham doesn't work that way.

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