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... because Ruby isn't terse enough yet

weblog.raganwald.com

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Re: ... because Ruby isn't terse enough yet

#11

Post by raganwald »

mechanical_fish wrote: post #9
mynameishere wrote: post #5

The Perl Golf anti-pattern.

I tend to agree with you. It's obvious to me that the following code evaluates to 6: r = 2 foo = lambda {|x| x * r} foo.call(3) And it's obvious to me that the following code raises an ArgumentError: foo = lambda {|x,r| x * r} foo.call(3) But what does this do? r = 2 bar = 'x*r'.to_proc bar(3) Do I get the 6, or do I get the ArgumentError? UPDATE: I presume the answer is "ArgumentError" (because the alternative appea…

"these folks"

There are at least two kinds of folks: those who are "fixing" Ruby the language, such as the Rubinius team, and those who are "using" the language.

I am in the latter camp. So sometimes I complain about what is broken--http://weblog.raganwald.com/2007/02/why-ruby-is-not-acceptab... sometimes I hack around it. But no, I am in no position to change the language. If I was, I would actually implement the point-free and underscore conventions natively.

If you want to use closures, you want to use lambda, not String#to_proc. If you dislike using .call, Ruby also allows [] syntax, so:

    r = 2
    foo = lambda {|x| x * r}
    foo.[3]
May be a little less objectionable.

Re: ... because Ruby isn't terse enough yet

#13

Post by mdemare »

mechanical_fish wrote: post #10
mdemare wrote: post #2

In Paul Graham's Accumulator Generator comparison ( http://www.paulgraham.com/accgen.html ) Ruby is now terser than any language except Arc. foo = 'n -> x -> n += x'.to_proc f = foo[4] f[2] # => 6 f[2] # => 8 (This would be even terser: foo = &'n -> x -> n += x' but the ampersand syntax is only allowed after a method call.)

For comparison, the original Ruby version: def foo (n) lambda {|i| n += i } end It's five characters longer, but approximately 350% more readable. Of course, a lot of that is because I'm more familiar with standard Ruby syntax than I am with this hack... but doesn't that tend to prove my point?

Well, by definition it's more readable, since nobody is familiar with the new notation yet. But objectively it has problems: unnecessary def and lambda keywords, using () and || for argument lists, using def .. end and {} for scopes. There's room for improvement.

Personally, I like many things from Haskell's syntax. I wish I could say this in Ruby:

    foo = n -> x -> n += x

Re: ... because Ruby isn't terse enough yet

#14

Post by mdemare »

mnemonicsloth wrote: post #12

What is a "point-free holomorphism" ? I study math, hack Scheme, and find myself totally confused by terminology. Maybe it's a riddle or something -- "What does complex-smoothness have to do with lambda calculus?"

The point-free style means avoiding lambda expressions: http://rickyclarkson.blogspot.com/2007/09/point-free-program...

Re: ... because Ruby isn't terse enough yet

#15

Post by raganwald »

mnemonicsloth wrote: post #12

What is a "point-free holomorphism" ? I study math, hack Scheme, and find myself totally confused by terminology. Maybe it's a riddle or something -- "What does complex-smoothness have to do with lambda calculus?"

It was actually a typo. Fixed, thank you.

Re: ... because Ruby isn't terse enough yet

#17

Post by neelesh »

mdemare wrote: post #2

In Paul Graham's Accumulator Generator comparison ( http://www.paulgraham.com/accgen.html ) Ruby is now terser than any language except Arc. foo = 'n -> x -> n += x'.to_proc f = foo[4] f[2] # => 6 f[2] # => 8 (This would be even terser: foo = &'n -> x -> n += x' but the ampersand syntax is only allowed after a method call.)

The python implementation looks overly complicated. I was thinking that the ruby and python implementations would be very similar. Here it goes

def foo(n):

    return lambda i:n+i
Tried it (Python 2.5) and it works.

Re: ... because Ruby isn't terse enough yet

#18

Post by mdemare »

neelesh wrote: post #17
mdemare wrote: post #2

In Paul Graham's Accumulator Generator comparison ( http://www.paulgraham.com/accgen.html ) Ruby is now terser than any language except Arc. foo = 'n -> x -> n += x'.to_proc f = foo[4] f[2] # => 6 f[2] # => 8 (This would be even terser: foo = &'n -> x -> n += x' but the ampersand syntax is only allowed after a method call.)

The python implementation looks overly complicated. I was thinking that the ruby and python implementations would be very similar. Here it goes def foo(n): return lambda i:n+i Tried it (Python 2.5) and it works.

Actually it doesn't work - calling the returned lambda should increment n - your implementation doesn't.

Re: ... because Ruby isn't terse enough yet

#19

Post by mechanical_fish »

raganwald wrote: post #11
mechanical_fish wrote: post #9

Earlier quoted context omitted.

I tend to agree with you. It's obvious to me that the following code evaluates to 6: r = 2 foo = lambda {|x| x * r} foo.call(3) And it's obvious to me that the following code raises an ArgumentError: foo = lambda {|x,r| x * r} foo.call(3) But what does this do? r = 2 bar = 'x*r'.to_proc bar(3) Do I get the 6, or do I get the ArgumentError? UPDATE: I presume the answer is "ArgumentError" (because the alternative appea…

"these folks" There are at least two kinds of folks: those who are "fixing" Ruby the language, such as the Rubinius team, and those who are "using" the language. I am in the latter camp. So sometimes I complain about what is broken-- http://weblog.raganwald.com/2007/02/why-ruby-is-not-acceptab... sometimes I hack around it. But no, I am in no position to change the language. If I was, I would actually implement the p…

I cannot get foo.[3] to work:

  syntax error, unexpected '['
But please don't spend too much time explaining what I'm doing wrong, because I'm afraid I don't like foo.[3] anyway. :)

Let me demonstrate my problem by taking a simulated tour through my brain as it encounters foo.[3] for the first time:

"WTF?

"Did someone mistype foo[3]?

"No, wait, surely it's supposed to be foo(3). I'm pretty sure that foo is a function. Didn't we set it equal to a lambda expression three lines ago?

"Maybe I need glasses. Let's adjust my monitor. No, those are square brackets, all right. And that really is a period between "foo" and the brackets.

"Maybe Google can help. But I'm not sure how to google '.[]'

"Oh, no -- is this one of those mysterious edge cases of the Ruby syntax? Do I hear _Why laughing at me? Does foo.[] magically target the eigenclass, or the metaclass, or the zetaclass, or something? Or did one of the libraries secretly redefine the core language behind my back?

"omigod, I should have learned Python.

"No, wait! The dot means that we're calling a method. And I know that [] is a method -- we redefine it all the time. So foo.[3] is just an obscure-ass way of calling foo[3] .

"Which makes no sense, because I thought foo was a function. So I must be wrong.

"WTF?"

[ten minutes later]

"Aargh! I went through ten minutes of confusion just to save three characters?"

I may have exaggerated this a little. And, yet, I really did have no idea that .[] works, and I still have no idea how it works. (Of course, in my version of Ruby, it apparently doesn't work, which makes it hard to investigate.)

Now, don't get me wrong -- Ruby is my favorite programming language. Quite often, after the tortured syntax, the monkey-patched class, or the strange new DSL stops you dead in your tracks, you'll struggle through the learning curve and discover that you have a powerful new technique. This starts on day zero of Ruby, when you see your first block. It looks like nothing on Earth, but it turns out to be insanely great.

Symbol#to_proc is a borderline case. I like the idea, but I hate the syntax. The &: doesn't bother me as much as the lack of curly brackets. To me, idiomatic Ruby is about blocks -- I expect map() and inject() and delete_if() to take blocks, not arguments. I would really prefer this:

  my_array.map {_.get_funky}
Reading this makes me happy. There's a map() call, so I expect a block, and look -- there are the curly brackets. And because it's a block, the stuff inside it must be a method call. And, in fact, the underscore and the dot mean that we're invoking a method on a placeholder. All is well with the world, and no higher brain functions need to be engaged.

But, you know, life isn't perfect. Language is about communication, and ultimately the language you speak is determined by what other people are speaking. Symbol#to_proc is powerful enough to become popular, and popular enough to be idiomatic, so we all have to learn it. Perhaps I'll even start using it.

But I'm afraid String#to_proc, like foo.[x], is past the point of diminishing returns. Do I really need a version of lambda that is not only utterly unlike Ruby's usual lambda, but is even less like Scheme's lambda? And are my colleagues really going to forgive me for asking them to learn Haskell syntax in order to read something as trivial as lambda {|x,y| x+y} ? I'm not even sure if I could forgive myself!

Re: ... because Ruby isn't terse enough yet

#20

Post by testapplication »

neelesh wrote: post #17
mdemare wrote: post #2

In Paul Graham's Accumulator Generator comparison ( http://www.paulgraham.com/accgen.html ) Ruby is now terser than any language except Arc. foo = 'n -> x -> n += x'.to_proc f = foo[4] f[2] # => 6 f[2] # => 8 (This would be even terser: foo = &'n -> x -> n += x' but the ampersand syntax is only allowed after a method call.)

The python implementation looks overly complicated. I was thinking that the ruby and python implementations would be very similar. Here it goes def foo(n): return lambda i:n+i Tried it (Python 2.5) and it works.

That should read:

    def foo(n):
        n = [n]
        def bar(i):
            n[0] += i
            return n[0]
        return bar
Python really needs a scoping syntax to allow assignment to closed variables.
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