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I wondered if there are any alternatives to Scala that attempt to offer a more powerful type system and syntax. I'm aware of functional alternatives such as Haskell, but are there any are really pushing the static OO side of things, for example in such areas, where Scala is lacking such as virtual classes, full multiple inheritance and more flexible constructor syntax, static contract checking, more powerful path dependence, MyTypes, friend modifier, first class imports, or maybe some esoteric typing tool, I haven't even thought of / heard of.

OO and to lesser extent Static do not seem to be fashionable these days. However, it strikes me that the power of modern computers enable the creation of static compilers way beyond the dreams of compiler writers in previous decades.

I presume as I haven't come across anything, there's no alternative that I'm likely to want to knock out production code in any time soon. But even if they're still very much academic languages, I'd still like to keep an eye on them and maybe play around with them. I'm particularly looking for what might be called left field alternatives to Scala. So not Ceylon or Kotlin that are trying to prioritise simplicity over power. Eiffel doesn't seem to be going anywhere these days. I've come across gBeta and Ceasar but haven't been able to work out if there are any areas where they lose out to Scala. Are there any other possibilities?

om-nom-nom
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Rich Oliver
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  • I think Scala's type system second to none, but in the interest of trying alternatives, have a look at [Ioke](http://ioke.org/). – opyate Jun 18 '12 at 12:05
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    Oops, I read "multi paradigm" and got excited about showing you Ioke :) – opyate Jun 18 '12 at 12:15
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    @Rich: What's wrong with Scala and Haskell? I don't think you'll get a much better type system than what's offered by those two. – Niklas B. Jun 18 '12 at 12:16
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    By the way, you should have a look at OCaml and F# as well. They're functional, object-oriented and statically typed. There's also the dependent-type based languages like Coq and Agda, which are unbeatable when it comes to the type system. – Niklas B. Jun 18 '12 at 12:19
  • I'd mention Ceylon with its emphasis on intersection and union types. http://ceylon-lang.org/documentation/tour/types/ – Michał Politowski Jun 18 '12 at 12:27
  • @NiklasB. I think Scala's a great language and I think it would have been even greater if it had been made for .net rather than the JVM, but I do miss full MI and friend from C++ – Rich Oliver Jun 18 '12 at 13:03
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    Well there is at least [an effort](http://www.scala-lang.org/node/168) to bring Scala to the .NET platform. – Niklas B. Jun 18 '12 at 13:20
  • @NiklasB. and even [for LLVM](http://greedy.github.com/scala-llvm/) – om-nom-nom Jun 18 '12 at 14:45
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    @Rich: With traits, you basically get the same thing you'd typically achieve using MI in C++. What exactly do you miss here? – Niklas B. Jun 18 '12 at 16:32

2 Answers2

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In a word, no. There are no popular OO alternatives that come anywhere close to Scala's type system. Given your desired features, I'd suggest you take a hard look at C++, D, and Go.

If you're feeling adventurous and you aren't completely attached to the idea of OO, then take a look at Typed Racket. Coq, Idris, and Agda offer dependently typed goodies that are quite intriguing. Or just turn to popular FP languages like Haskell, F#, and OCaml.

Is there any particular reason you want an OO language? Again, Scala is probably as good as it gets right now if you want a cool type system and OO.

Dan Burton
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  • All my time with C# I wanted multiple inheritance and fancied path dependant types, although I didn't know the name. Having purged my application of self types and started using classic MI diamonds it seems pretty good. The things I'd most like is to be able to create classes that extend path dependant types outside of the path, in the way you extend a generic class without closing the type constructor and easy runtime compilation. – Rich Oliver Jun 21 '12 at 01:43
  • I am currently focusing on Scala; have come from Object oriented Programming Paradigm and trying to grasp Functional Programming paradigm . I appreciate your answer to my question at http://stackoverflow.com/questions/11162743/haskell-scala-interoperability . I am ready to leave behind OO knowledge. Can Scala be completely replaced with Haskell for ERP (Enterprise Resource Planning) like large scale multi location distributed application? – Optimight Jun 23 '12 at 00:24
  • @Optimight sure. You might want to look into the [Industrial Haskell Group](http://industry.haskell.org/), see examples of [Haskell in industry](http://www.haskell.org/haskellwiki/Haskell_in_industry), and talk to people on the [#haskell irc channel](http://www.haskell.org/haskellwiki/IRC_channel) for details. – Dan Burton Jun 23 '12 at 01:15
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D (specifically, D version 2, aka D2) is pretty much exactly the language you're looking for.

There are videos on Youtube introducing D, IDEs/plugins like Visual D (plugin for Visual C++), Mono-D (plugin for MonoDevelop), and DDT (plugin for Eclipse).

The main site at dlang.org has a full library reference, language syntax, tutorials, forums for beginners/advanced discussions, etc.

For a GUI, look at GtkD. I believe you need to use the DMD compiler for this, currently.

dsource.org and github have many other third-party libraries/code, but you'll find that the core library includes all the basics, like json parsers, XML parsers, etc., and the core language has many things you need built-in, like hashmaps, dynamic arrays, design by contract, statically evaluated templates/expressions, etc.

With D2, you can link directly to C and C++, and bind to Python/LUA code, etc. It's capable as a systems language (you CAN write an OS with it, if you want), but also works well as a modern, high-level, elegant, rapid application language with support for things like concurrent, safe code.

All in all, it's very impressive. Sad that it's not more popular, given that Scala is a slow memory hog by comparison ;)