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> I understand it's normal usage syntax very well. You understand C++ syntax because you're familiar with it, not because it is "normal" in any way.

by VMG 12y ago

72deluxe 12y ago
Very true, but helpfully many other languages have a similar syntax (C, Java, JavaScript, even PHP's OOP system looks like Java) so it is easy to move between them. This looks very alien. Is there any language with a similar syntax?
- lmm 12y ago
  Yes, plenty of other functional languages. I have literally never seen a line of Haskell before but I know ML, Scala and Python, so I can read the line pretty easily: primes = sieve[2..] where sieve (p:xs) = p : sieve [x | x <- xs, x `mod` p /= 0] [2..] is a list starting at 2; "where" is pretty clearly defining the function after using it. So sieve is a function; p:xs is a destructuring assignment or pattern or whatever you call it (I mean, xs clearly isn't a type, so I guess Haskell writes lists as 1 : 2 : 3 : Nil, where Scala or ML would use ::). (Which means this is a function that only works on a nonempty list, which seems a bit sneaky, but we can see that it's never going to be called for an empty one). So sieve(p:xs) returns p:sieve(...), a fairly straightforward recursion. And the ... is fairly obviously a list comprehension I'd write in Python as "[x for x in xs if x % p != 0]". Did I get it right? The language certainly has an excess of symbols - I think the Python way of writing that list comprehension is much clearer - but it's certainly not incomprehensible; the "where" makes perfect sense, and the [] make a good visual distinction. The : form of lists is not the C way, but it's by no means unknown. The destructuring assignment might be unfamiliar, but once you've got that p:xs is a list there's only really one thing it could mean (and even in Python you can write (a, b) = something()). To a non-Haskeller it's kind of surprising that the code doesn't stack overflow from infinite recursion, but again, given that the code works, there's only one thing it could possibly mean. This was much easier than the time when I tried to read some Clojure. Edit: Just to be sure I got it, I rewrote the one-liner in Python. Had to use generators to get the laziness, and had to split it in two lines for the function: def sieve(xs): p = next(xs); yield p; yield from sieve(x for x in xs if x % p != 0) primes = sieve(itertools.count(2)) Is that clearer than the Haskell? Maybe.
- orbifold 12y ago
  The syntax should not really be a primary concern when evaluating a new language. It is easy enough to pick up if you understand the concepts behind the language. Haskell has not all that many keywords and a lot of syntactic sugar, there are no public final static member variables and no insane *((&a)++)++.
  - 72deluxe 12y ago
    That's a good attitude to have when approaching a new language. I should try a new language, if and when I have a need or need to learn some new concepts.

> I understand it's normal usage syntax very well. You understand C++ syntax because you're familiar with it, not because it is "normal" in any way.

by VMG 12y ago

> I understand it's normal usage syntax very well. You understand C++ syntax because you're familiar with it, not because it is "normal" in any way.

72deluxe 12y ago

Very true, but helpfully many other languages have a similar syntax (C, Java, JavaScript, even PHP's OOP system looks like Java) so it is easy to move between them. This looks very alien. Is there any language with a similar syntax?

lmm 12y ago
Yes, plenty of other functional languages. I have literally never seen a line of Haskell before but I know ML, Scala and Python, so I can read the line pretty easily: primes = sieve[2..] where sieve (p:xs) = p : sieve [x | x <- xs, x `mod` p /= 0] [2..] is a list starting at 2; "where" is pretty clearly defining the function after using it. So sieve is a function; p:xs is a destructuring assignment or pattern or whatever you call it (I mean, xs clearly isn't a type, so I guess Haskell writes lists as 1 : 2 : 3 : Nil, where Scala or ML would use ::). (Which means this is a function that only works on a nonempty list, which seems a bit sneaky, but we can see that it's never going to be called for an empty one). So sieve(p:xs) returns p:sieve(...), a fairly straightforward recursion. And the ... is fairly obviously a list comprehension I'd write in Python as "[x for x in xs if x % p != 0]". Did I get it right? The language certainly has an excess of symbols - I think the Python way of writing that list comprehension is much clearer - but it's certainly not incomprehensible; the "where" makes perfect sense, and the [] make a good visual distinction. The : form of lists is not the C way, but it's by no means unknown. The destructuring assignment might be unfamiliar, but once you've got that p:xs is a list there's only really one thing it could mean (and even in Python you can write (a, b) = something()). To a non-Haskeller it's kind of surprising that the code doesn't stack overflow from infinite recursion, but again, given that the code works, there's only one thing it could possibly mean. This was much easier than the time when I tried to read some Clojure. Edit: Just to be sure I got it, I rewrote the one-liner in Python. Had to use generators to get the laziness, and had to split it in two lines for the function: def sieve(xs): p = next(xs); yield p; yield from sieve(x for x in xs if x % p != 0) primes = sieve(itertools.count(2)) Is that clearer than the Haskell? Maybe.
orbifold 12y ago
The syntax should not really be a primary concern when evaluating a new language. It is easy enough to pick up if you understand the concepts behind the language. Haskell has not all that many keywords and a lot of syntactic sugar, there are no public final static member variables and no insane *((&a)++)++.
- 72deluxe 12y ago
  That's a good attitude to have when approaching a new language. I should try a new language, if and when I have a need or need to learn some new concepts.