It's very hard to find good tutorials on APL because it's not very popular and most of its implementations are closed-source and not compatible with each other's language extensions, but it's most recognizable for its extreme use of non-standard codepoints. Every function in APL is defined by a single character, but those characters range from . to most of the Greek alphabet (taking similar meanings as in abstract math) to things like ⍋ (sort ascending). Wikipedia has a few fun examples if you just want a very brief taste; you can also read a tutorial from MicroAPL at http://www.microapl.com/apl/tutorial_contents.html
It's mostly good for being able to express mathematical formulas with very little translation from the math world - "executable proofs," I think the quote is - and having matrices of arbitrary dimension as first-class values is unusual if not unique. But for any practical purpose it's to Haskell what Haskell is to Java.
> But for any practical purpose it's to Haskell what Haskell is to Java.
Can you elaborate on this? As I understand, the core strengths of APL are succinct notation, built-in verbs which operate on vectors/matrices, and a requirement to program in a point-free style. All of this can be done in Haskell.
>A Haskell programmer unfamiliar with APL looks at an APL program and...
And says "what's the big deal?". That's exactly the question, what is the big deal. APL isn't scary, I'm not shouting "I can't make sense of this", I am asking "how is this better than haskell in the same way haskell is better than java?".
I'm not imagined, I am real. I know you were restating the analogy, the problem is that the analogy is wrong. I can't find anything about APL that a haskell developer would find new or interesting or frightening or anything like that.
More esoteric organization/concepts for anyone coming from the C family (which is basically everyone), more out-there notation, more deserving of the title "write-only," and less ability to do anything you might want to do with a real computer beyond using it as a calculator. I wouldn't want to do much work with Haskell's GTK bindings, but at least they exist.
That tutorial is deeply unimpressive. It seems very excited about APL having functions, and not directly mapping to machine-level constructs. In 1962 I can imagine that being impressive (if you weren't familiar with Lisp or ALGOL); today, not so much. The one thing that does seem somewhat interesting is the emphasis it puts on "operators" (i.e., second-order functions). This is obviously not new to anyone familiar with functional programming, but I do like the way that tutorial jumps in quite quickly to the practical utility of a few simple second-order functions (reduce, product, map).
Like I said, it's hard to find good ones; I didn't say I had succeeded. I learned a bit of it for a programming language design course, but I never got beyond the basic concepts.
It's mostly good for being able to express mathematical formulas with very little translation from the math world - "executable proofs," I think the quote is - and having matrices of arbitrary dimension as first-class values is unusual if not unique. But for any practical purpose it's to Haskell what Haskell is to Java.