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Two reasons. First, they are both languages with useful type systems. There's not many languages in that group. Second, ocaml is a multiparadigm language for

Two reasons. First, they are both languages with useful type systems. There's not many languages in that group. Second, ocaml is a multiparadigm language for real, and with a focus of functional first. Python, ruby, perl, etc are procedural/OO languages that have map and filter. It is a huge pain and tons of extra code to write a program in functional style in python, it is lacking basically everything. It is normal to write a program in a functional style in ocaml. If you learn haskell first, ocaml will serve no purpose for you. But for someone coming from imperative land, learning ocaml can be a helpful half-way house on the way to haskell.

silentOpen 13y ago
As always, it depends on the job. For some systems, OCaml is superior; for others, Haskell is superior. One big question informing the choice is "do I want to program primarily lazily or primarily eagerly?" Another is "is time to achieve system performance a big factor in success?" If eager, performance-eager -> Ocaml If lazy, performance-lazy -> Haskell
- nousernamesleft 13y ago
  Having spent 6 years with ocaml, I can honestly say I both never wrote anything where ocaml offered a benefit haskell does not, and can not even think of such a program. You pose two questions, one of which is effectively irrelevant, and the other I believe is based on an incorrect assumption. Maybe 5% of code the evaluation strategy matters. It makes no difference whether you are adding strictness for 2% of your code or adding laziness for 2% of your code. The performance question I think is a misconception. Do you have any evidence to suggest it is easier to write fast code in ocaml? I've never found a person who has used both languages and felt that was the case. I've only found people without haskell experience believing that via second (or third, or fiftieth) hand rumors. Ocaml offers two things over haskell. One, imperative constructs. This matters for people making a transition to functional programming, but not for people who've finished that transition. Second, the compiler is fast. I don't mean generates fast code, ghc does that too. I mean it generates code quickly. This is an annoyance with ghc, no question. Haskell offers a lot over ocaml. A useful standard library. Cabal and hackage. Parallelism done right, out of the box (super cheap green threads multiplexed over a pool of OS threads). Tons of libraries that don't exist in ocaml, everywhere from attoparsec and aeson, to binary and lenses, pipes-concurrency and STM. A community that is ten times the size of ocaml's. There are good reasons it has gone from ocaml having the larger community to haskell dwarfing ocaml in community size, language usage, library availability, etc. in the last decade.
  - deleted 13y ago
    [deleted]
  - anaphor 13y ago
    OCaml has camlp4 which is vastly superior to TH for extending the language's syntax.
  - danieldk 13y ago
    Do you have any evidence to suggest it is easier to write fast code in ocaml? I find it much easier. To give one example: I recently had to write some code that shuffles arrays based on a PRNG. In OCaml, one can simply use a mutable array and a PRNG that uses a mutable variable. In Haskell, efficient array mutation is possible, but you have to do it in the ST or IO monad. So, in a pure function you'll want to runST an expression in the ST monad. But then you need to thread the 'state' of the random number generator in function calls, or use a State-like monad. If you use a state monad, you have two monads and will probably use a monad transformer. Writing the equivalent Haskell code is much more work. But on the other side, Haskell keeps you more honest. The end result is that in Haskell, it is guaranteed that the end-result is pure (if you don't use unsafePerformIO of course). In OCaml it's only by convention. Which is better depends on what you want, convenience or safety. Personally, if I have to choose between OCaml or Haskell, I'll choose the latter. There are already plenty of languages that are pragmatic and less strongly typed. For me, OCaml provides relatively only advantages over strongly-typed imperative languages that support closures, etc. Haskell on the other hand, provides an amount of type-safety that those languages do not provide, while still being usable (both as a language and in terms of the library ecosystem).
    - nousernamesleft 13y ago
      >I find it much easier Ok, but your anecodes + my anecdotes = still just anecdotes. To support the claim that it is easier to write fast code in ocaml, we need to find evidence. >Writing the equivalent Haskell code is much more work I have not experienced anything like that, despite having much more experience with ocaml than with haskell. You are imposing limitations on yourself when using haskell and then saying haskell is imposing them. Every ocaml function is in IO, it just doesn't provide type information to tell you that. So doing the same thing in haskell is doing it in IO, which requires no special effort at all. Even if you choose to add a purity restriction on yourself, adding "runST $" does not seem like a lot of work to me.
agentultra 13y ago
> It is a huge pain and tons of extra code to write a program in functional style in python, it is lacking basically everything I've had the exact opposite experience. I write my Python code in a functional style by default. I use mutation as an exception rather than the rule. I find my code to be much more terse overall. When used effectively I find functional Python requires less code, not more as you imply.
- nousernamesleft 13y ago
  I suspect the difference of opinion is due to a different understanding of what a functional style is. Python does not have tail call elimination. You literally can not write lots of normal functional programs in python. Python doesn't have currying and requires explicit extra code to create partially applied functions. This makes functional programming painful and verbose. I think you are writing what I would call imperative code that uses some functional constructs where it is shorter. No doubt that is shorter than sticking entirely to imperative code, but it is a far cry from writing a program in functional style which requires that you not use imperative constructs.
- codygman 13y ago
  Some pythonistas get very annoyed when I do the same.

silentOpen 13y ago

As always, it depends on the job. For some systems, OCaml is superior; for others, Haskell is superior. One big question informing the choice is "do I want to program primarily lazily or primarily eagerly?" Another is "is time to achieve system performance a big factor in success?" If eager, performance-eager -> Ocaml If lazy, performance-lazy -> Haskell

nousernamesleft 13y ago
Having spent 6 years with ocaml, I can honestly say I both never wrote anything where ocaml offered a benefit haskell does not, and can not even think of such a program. You pose two questions, one of which is effectively irrelevant, and the other I believe is based on an incorrect assumption. Maybe 5% of code the evaluation strategy matters. It makes no difference whether you are adding strictness for 2% of your code or adding laziness for 2% of your code. The performance question I think is a misconception. Do you have any evidence to suggest it is easier to write fast code in ocaml? I've never found a person who has used both languages and felt that was the case. I've only found people without haskell experience believing that via second (or third, or fiftieth) hand rumors. Ocaml offers two things over haskell. One, imperative constructs. This matters for people making a transition to functional programming, but not for people who've finished that transition. Second, the compiler is fast. I don't mean generates fast code, ghc does that too. I mean it generates code quickly. This is an annoyance with ghc, no question. Haskell offers a lot over ocaml. A useful standard library. Cabal and hackage. Parallelism done right, out of the box (super cheap green threads multiplexed over a pool of OS threads). Tons of libraries that don't exist in ocaml, everywhere from attoparsec and aeson, to binary and lenses, pipes-concurrency and STM. A community that is ten times the size of ocaml's. There are good reasons it has gone from ocaml having the larger community to haskell dwarfing ocaml in community size, language usage, library availability, etc. in the last decade.
- deleted 13y ago
  [deleted]
- anaphor 13y ago
  OCaml has camlp4 which is vastly superior to TH for extending the language's syntax.
- danieldk 13y ago
  Do you have any evidence to suggest it is easier to write fast code in ocaml? I find it much easier. To give one example: I recently had to write some code that shuffles arrays based on a PRNG. In OCaml, one can simply use a mutable array and a PRNG that uses a mutable variable. In Haskell, efficient array mutation is possible, but you have to do it in the ST or IO monad. So, in a pure function you'll want to runST an expression in the ST monad. But then you need to thread the 'state' of the random number generator in function calls, or use a State-like monad. If you use a state monad, you have two monads and will probably use a monad transformer. Writing the equivalent Haskell code is much more work. But on the other side, Haskell keeps you more honest. The end result is that in Haskell, it is guaranteed that the end-result is pure (if you don't use unsafePerformIO of course). In OCaml it's only by convention. Which is better depends on what you want, convenience or safety. Personally, if I have to choose between OCaml or Haskell, I'll choose the latter. There are already plenty of languages that are pragmatic and less strongly typed. For me, OCaml provides relatively only advantages over strongly-typed imperative languages that support closures, etc. Haskell on the other hand, provides an amount of type-safety that those languages do not provide, while still being usable (both as a language and in terms of the library ecosystem).
  - nousernamesleft 13y ago
    >I find it much easier Ok, but your anecodes + my anecdotes = still just anecdotes. To support the claim that it is easier to write fast code in ocaml, we need to find evidence. >Writing the equivalent Haskell code is much more work I have not experienced anything like that, despite having much more experience with ocaml than with haskell. You are imposing limitations on yourself when using haskell and then saying haskell is imposing them. Every ocaml function is in IO, it just doesn't provide type information to tell you that. So doing the same thing in haskell is doing it in IO, which requires no special effort at all. Even if you choose to add a purity restriction on yourself, adding "runST $" does not seem like a lot of work to me.

agentultra 13y ago

> It is a huge pain and tons of extra code to write a program in functional style in python, it is lacking basically everything I've had the exact opposite experience. I write my Python code in a functional style by default. I use mutation as an exception rather than the rule. I find my code to be much more terse overall. When used effectively I find functional Python requires less code, not more as you imply.

nousernamesleft 13y ago
I suspect the difference of opinion is due to a different understanding of what a functional style is. Python does not have tail call elimination. You literally can not write lots of normal functional programs in python. Python doesn't have currying and requires explicit extra code to create partially applied functions. This makes functional programming painful and verbose. I think you are writing what I would call imperative code that uses some functional constructs where it is shorter. No doubt that is shorter than sticking entirely to imperative code, but it is a far cry from writing a program in functional style which requires that you not use imperative constructs.
codygman 13y ago
Some pythonistas get very annoyed when I do the same.