Code iOS Apps in OCaml

by amirmc • 14 years ago

62 26 14 years ago

ootachi• 14 years ago

OCaml is a highly underappreciated language. The biggest problem is the haphazard syntax, but if you can get over that, it's really a joy to use for application programming. You get the strongly-typed, type-inferred, functional aspects of Haskell, but without the drawbacks of laziness (for example, you can safely do IO outside the IO monad, and space leaks are less common) and with a simpler type system. There are no null pointers, and coupled with exhaustiveness checks in pattern matching, you frequently find that "if it compiles, it works". The compiler is a simple non-optimizing compiler, but it's more mature than, for example, that of Go (especially in the GC), so it beats Go in performance.

sgdesign• 14 years ago

It seems like a lifetime ago, but I actually spent one year in college mainly learning OCaml.

The language is really elegant, but I'm not sure I ever saw a real-life use for it until today.

colomon• 14 years ago

Unison: http://www.cis.upenn.edu/~bcpierce/unison/index.html

In fact I think this is the only software that I know is written in a functional language that I use on a regular basis. I've always figured that said very good things about OCaml. (Not that I've ever gotten around to learning OCaml, mind you.)

gecko3• 14 years ago

Having suffered through C++ for several years, and having enjoyed writing SML/NJ, the syntax doesn't bother me at all.

My big problem with OCaml is that the ecosystem is insanely poorly documented, and, if I understand this right (I am definitely not an OCaml expert), fractured. E.g., there's a lot of buzz about Jane Street's library, but, as far as I can tell, your code uses only their library or the built-in one, but not both. There's also several different build systems (ocamlbuild and ocaml-make spring to mind), and it's not clear to me which is preferred, nor how to deal with the fact that interesting-looking libraries seem split on which to use, meaning I'm guessing I need to somehow glue the systems together. There are several libraries for unicode support, but again, I don't know which (if any) is the "normal" one, and various libraries appear to use different unicode support libs, so I have no idea whether they can safely be mixed in a single application. And then there's this whole GODI thing, which appears to be kind of like RVM or perlbrew, but kind of its own thing. And so on.

What I'd love is a well-written, super-opinionated guide that says, "Okay, use ocamlbuild for building, use Jane Street's Async lib for multitasking, use GODI to manage your system and here's how you do that, grab this Unicode library, and you'll be good to write stuff that other people can easily use and maintain."

Arelius4• 14 years ago

There are a lot of problems with C++, but I've hardly heard syntax referred to as one of them.

avsm2• 14 years ago

Your request for a super-opinionated guide "get stuff done" guide will be available soon; http://realworldocaml.org

michaelochurch3• 14 years ago

OCaml's largest problems, IMO, are:

1. Global interpreter-lock, and the effect that has on the ability to write multi-threaded programs.

2. False negative proof, the same issue Haskell has. The fact that it's "had its chance" to catch on and hasn't done so marks it as a failure (or "not production ready") in the eyes of people who make decisions.

Scala has better odds than Ocaml and Haskell for this reason alone.

3. The perception that there's a lack of libraries relative to, say, the JVM. I say "perception" because Ocaml has bindings to leverage the C libraries. However, it doesn't have the Java libraries, and those are proving to be an important asset even in un-Javay languages like Clojure.

On Scala, since I'm resigned to the fact that it is more likely to win (and find I like the language a lot) the unresolved question in my mind is: is Scala an acceptable ML? I like Scala a lot and I'm leaning toward "Yes", but I haven't worked with Scala on something big enough to have a fully formed opinion there.

4. (Small one.) The name. I would like it just as much if it were called FishGuts, but names matter in adoption. I think Ocaml's a fine name, but I'm weird.

Arelius4• 14 years ago

The global interpreter lock is a large one IMO. One of the huge advantages of type safety is that you can use types to help enforce thread safety rules, but if the interpreter itself can't handle it, that's a huge problem!

technomancy• 14 years ago

> is Scala an acceptable ML?

I thought it might be until I tried OCaml, and the difference between type inference that only works on locals and pervasive inference is huge. Also the fact that JVM interop makes it hard to avoid null pointers is a big strike against it.

Still, I agree that the odds are in its favour vs OCaml for things that don't need to be close to the metal.

Dn_Ab• 14 years ago

I do not think Scala is an ML. The use of the word acceptable and indeed restricting it to an ML derivative loses the point of what Scala is supposed to be. Scala is supposed to be something different: a successful melding of OOP and functional. And it is the best at that I have seen. It succeeds on this better than the next biggest contender: F#, which is the most acceptable ML, IMO. F# is more typically functional, using the usual Hindley Milner Inference and sharing a core with OCaml but with significant whitespace. So it can be very succinct. Typically functional idioms like algebraic data types, Piping, point free, currying and combinators is more natural to F# than Scala's more OOP way. I prefer F# to Scala but that is merely a subjective preference.

There are a number of things that Scala does naturally that are cumbersome in other languages because of how it manages to meld a powerful combination of orthogonal features. To use Scala as just another functional language is to miss its power. Those who criticize OOP have not used a language that does it right. Abstractly, in a simplified categoric setting, we can consider OOP (objects as coalgebras) and FP (algebraic data types) as duals of each other. A proper unification of the concepts gives something more powerful than either. I think Scala comes the closest. Sure you can be 100% functional in it, or replicate Java but to call it one or the other is to make the same mistake as to say that light is both a wave and a particle and think you understand what that means.

swah2• 14 years ago

I find the syntax elegant...

li• 14 years ago

is it possible to just change syntax and keep the rest of ocaml system. For the syntax we can borrow ideas from Ruby or Python.

anders0• 14 years ago

Well the revised syntax (http://caml.inria.fr/pub/docs/manual-camlp4/manual007.html) is completely implemented as a camlp4 (p5?) extension, so if you have enough patience you can write another extension to replace the syntax with whatever you want, I suppose.

ramses• 14 years ago

OCaml would be my main and only language if it had real concurrency ... but I'll definitely have to give this a try.

mwerty• 14 years ago

Is there a Haskell equivalent?

Code iOS Apps in OCaml

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