39 ms·

Ela, dynamic functional language

45 points by T-A 12y ago

howling 11y ago
From what I see it is pretty similar to Haskell besides some minor syntax differences, strict evaluation by default, and dynamic typing. So why should I use this over Haskell?
- tel 11y ago
  The typing variation feels like it's going to so strongly change the pragmatic use of this language that the best I could say is that it is very distantly inspired by Haskell.
FraaJad 11y ago
very similar to pure - http://purelang.bitbucket.org/ http://purelang.bitbucket.org/ (not purescript).
- JadeNB 11y ago
  What makes you think of Pure, as opposed to Haskell as mentioned on the page and by howling (https://news.ycombinator.com/item?id=9555980 https://news.ycombinator.com/item?id=9555980)? The influence of Haskell is clear, but it's not so obvious to me that this language uses term rewriting (as in Pure) in any fundamental way. Maybe I missed it?
sgeisenh 11y ago
Ela is a type safe, strictly typed language, which is, however, not burden by limitations of any particular type checker. By nature, a language which is type safe and strictly typed must be burdened by the limitations of a "particular type checker." This is weak type safety at best. And it looks like there are runtime class checks, so you have all of the traditional drawbacks of dynamic languages.
- dllthomas 11y ago
  In principle, the type checker could be pluggable. That would mean the language isn't burdened by the limitations of any particular type checker, although it would almost certainly be burdened by complications at the boundaries of where one type checker is used versus another. It also might be reasonable to insist that such a system represents a family of languages rather than a single one.
JadeNB 11y ago
The language proudly boasts on its home page that its `head` function has the same wart as Haskell's (i.e., not handling empty lists)? Combining this with an explicit use of the `Option` monad just seems like teasing. (EDIT: Oops, I meant its "distinctive features" page http://elalang.net/About.aspx#features http://elalang.net/About.aspx#features , under "Algebraic Types".) (It's just my assumption that it doesn't handle empty lists, because it returns the literal first element of a non-empty one; but neither the Prelude http://elalang.net/docs/Article.aspx?p=lib\prelude.htm http://elalang.net/docs/Article.aspx?p=lib\prelude.htm nor the list module http://elalang.net/docs/Article.aspx?p=lib\list.htm http://elalang.net/docs/Article.aspx?p=lib\list.htm seems explicitly to mention the `head` function on lists (as opposed to strings or sequences) at all, so it's hard to say for sure.)
- tome 11y ago
  The "About" page that you linked has the code x = head xs //x is Some 1 which suggests 'head' is of type 'a -> Option a' and does not have the wart you are talking about.
  - tel 11y ago
    The example is a bit misleading there. To be more clear using types there's xs :: [Maybe Int] head xs :: Maybe Int
    - tome 11y ago
      Oh yeah, silly me!
  - JadeNB 11y ago
    As tel mentioned (https://news.ycombinator.com/item?id=9556393 https://news.ycombinator.com/item?id=9556393), this strange choice of list is why I said that combining `head` with an explicit (and, I think, misleading) use of the `Option` monad seemed like teasing.
    - tome 11y ago
tel 11y ago
Reading about this language gives me such a strange feeling. It makes me think of the cargo cults who worship airplane tributes due to once an airplane landing and providing supplies. Ela is clearly inspired by Haskell. It copies syntax and surface-level features mercilessly. It's also devoted to being dynamically typed which dramatically undermines the meaning and development of those very features. It makes for an interesting experiment. I can't say whether or not a dynamic language of this design is easy to work in compared with others. But I read things like Ela's "algebraic data types" and shudder a bit (and then a lot when I find the "Circle (& 'hello')" example). They're definitely inspired by ADTs, but also definitely nothing similar. These ADTs are that alien from MIB who steals human skin---on the surface you might confuse them, but a different sort of life boils underneath.
ColinWright 11y ago
Oh look, one of my pet hates. Displaying a sieve that claims to be the Sieve of Eratosthenes, and yet it does modulo tests, and hence isn't. Edit: It was by chance that it happened to be the example in the "A taste of Ela" box at the top. Reloading the page makes the example change to something else, so if you are wondering what I'm talking about, reload the page until the "taste" box explicitly calls something the Sieve of Eratosthenes. It isn't.
- JadeNB 11y ago
  I guess that the Sieve of Eratosthenes is the algorithm implemented in http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf ?
  - ColinWright 11y ago
    That paper does correctly deal with the issue. The conclusions in section 4 give an excellent summary.
- michaelcampbell 11y ago
  For those not wanting to click reload a slew of times (it took me about 3 minutes of clicking!)... //Sieve of Eratosthenes primes xs = sieve xs where sieve [] = [] sieve (p::xs) = & p :: sieve [& x \\ x <- xs | x % p > 0] //Outputs: [2,3,5,7] primes [2..10]
loqi 11y ago
> Unlike many other languages, Ela doesn't make any trade-offs, trying to combine distinct programming paradigms that don't fit well together. The author may want to tone down that claim - combining Haskell-style FP with dynamic typing certainly entails some trade-offs, regardless of whether or not they think it's a good idea.

45 points by T-A 12y ago

From what I see it is pretty similar to Haskell besides some minor syntax differences, strict evaluation by default, and dynamic typing. So why should I use this over Haskell?

tel 11y ago
The typing variation feels like it's going to so strongly change the pragmatic use of this language that the best I could say is that it is very distantly inspired by Haskell.

FraaJad 11y ago

very similar to pure - http://purelang.bitbucket.org/ http://purelang.bitbucket.org/ (not purescript).

JadeNB 11y ago
What makes you think of Pure, as opposed to Haskell as mentioned on the page and by howling (https://news.ycombinator.com/item?id=9555980 https://news.ycombinator.com/item?id=9555980)? The influence of Haskell is clear, but it's not so obvious to me that this language uses term rewriting (as in Pure) in any fundamental way. Maybe I missed it?

sgeisenh 11y ago

Ela is a type safe, strictly typed language, which is, however, not burden by limitations of any particular type checker. By nature, a language which is type safe and strictly typed must be burdened by the limitations of a "particular type checker." This is weak type safety at best. And it looks like there are runtime class checks, so you have all of the traditional drawbacks of dynamic languages.

dllthomas 11y ago
In principle, the type checker could be pluggable. That would mean the language isn't burdened by the limitations of any particular type checker, although it would almost certainly be burdened by complications at the boundaries of where one type checker is used versus another. It also might be reasonable to insist that such a system represents a family of languages rather than a single one.

JadeNB 11y ago

The language proudly boasts on its home page that its `head` function has the same wart as Haskell's (i.e., not handling empty lists)? Combining this with an explicit use of the `Option` monad just seems like teasing. (EDIT: Oops, I meant its "distinctive features" page http://elalang.net/About.aspx#features http://elalang.net/About.aspx#features , under "Algebraic Types".) (It's just my assumption that it doesn't handle empty lists, because it returns the literal first element of a non-empty one; but neither the Prelude http://elalang.net/docs/Article.aspx?p=lib\prelude.htm http://elalang.net/docs/Article.aspx?p=lib\prelude.htm nor the list module http://elalang.net/docs/Article.aspx?p=lib\list.htm http://elalang.net/docs/Article.aspx?p=lib\list.htm seems explicitly to mention the `head` function on lists (as opposed to strings or sequences) at all, so it's hard to say for sure.)

tome 11y ago
The "About" page that you linked has the code x = head xs //x is Some 1 which suggests 'head' is of type 'a -> Option a' and does not have the wart you are talking about.
- tel 11y ago
  The example is a bit misleading there. To be more clear using types there's xs :: [Maybe Int] head xs :: Maybe Int
  - tome 11y ago
    Oh yeah, silly me!
- JadeNB 11y ago
  As tel mentioned (https://news.ycombinator.com/item?id=9556393 https://news.ycombinator.com/item?id=9556393), this strange choice of list is why I said that combining `head` with an explicit (and, I think, misleading) use of the `Option` monad seemed like teasing.
  - tome 11y ago

tel 11y ago

Reading about this language gives me such a strange feeling. It makes me think of the cargo cults who worship airplane tributes due to once an airplane landing and providing supplies. Ela is clearly inspired by Haskell. It copies syntax and surface-level features mercilessly. It's also devoted to being dynamically typed which dramatically undermines the meaning and development of those very features. It makes for an interesting experiment. I can't say whether or not a dynamic language of this design is easy to work in compared with others. But I read things like Ela's "algebraic data types" and shudder a bit (and then a lot when I find the "Circle (& 'hello')" example). They're definitely inspired by ADTs, but also definitely nothing similar. These ADTs are that alien from MIB who steals human skin---on the surface you might confuse them, but a different sort of life boils underneath.

ColinWright 11y ago

Oh look, one of my pet hates. Displaying a sieve that claims to be the Sieve of Eratosthenes, and yet it does modulo tests, and hence isn't. Edit: It was by chance that it happened to be the example in the "A taste of Ela" box at the top. Reloading the page makes the example change to something else, so if you are wondering what I'm talking about, reload the page until the "taste" box explicitly calls something the Sieve of Eratosthenes. It isn't.

JadeNB 11y ago
I guess that the Sieve of Eratosthenes is the algorithm implemented in http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf ?
- ColinWright 11y ago
  That paper does correctly deal with the issue. The conclusions in section 4 give an excellent summary.
michaelcampbell 11y ago
For those not wanting to click reload a slew of times (it took me about 3 minutes of clicking!)... //Sieve of Eratosthenes primes xs = sieve xs where sieve [] = [] sieve (p::xs) = & p :: sieve [& x \\ x <- xs | x % p > 0] //Outputs: [2,3,5,7] primes [2..10]

loqi 11y ago

> Unlike many other languages, Ela doesn't make any trade-offs, trying to combine distinct programming paradigms that don't fit well together. The author may want to tone down that claim - combining Haskell-style FP with dynamic typing certainly entails some trade-offs, regardless of whether or not they think it's a good idea.