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I started learning Scala almost a year ago at my latest job - we use it for production systems at a large multinational investment bank. Coming to Scala from e

I started learning Scala almost a year ago at my latest job - we use it for production systems at a large multinational investment bank. Coming to Scala from experience including C, Java and Haskell, I intially found Scala quite difficult. It is true that there are some things in Scala that are not obvious to newcomers, and that are difficult to discover for yourself - such as the use of Implicits, and the strange precedence and binding rules for operator syntax. That said, it doesn't take long to learn, and once you do, it all makes sense. There are other great languages out there (I'd say Haskell is one), but compared to for example Java, or one of the dynamically typed languages, Scala is superb. Types, whilst not having the full H-M inference, are brilliant. That the author complains about having types rather than a simple map for keys shows a misunderstanding of what they are there for - the idea is to allow the compiler to prove at run-time what is valid code and what isn't. He comments that tests run too slowly in Scala (they don't - for our production systems building in SBT, a typical test run is significantly less than 10 seconds) but a lot of the time I don't even need to go that far - my IDE already highlights errors in the code as I type, where I have passed in incorrect or insufficient data. Also, the author makes a strange comment that H-M 'enabled' Monads, and the comment is written in a way that implies that Scala does not have Monads. This is incorrect. Scala has monads, and the Scalaz library has huge support for Monadic programming. We use Monads and Applicative Functors (a close relative) daily to build high level abstractions, and we couldn't live without them. In Scala we say flatMap rather than bind (or >>=), but we mean the same thing. Although thanks to the same flexible method naming that the author complains about, you can in fact say >>= if you wish. If you've only got a couple of days to use a language, and you're using it for a tiny project, then Scala is not for you. If want to learn a language that can make you vastly more productive whilst at the same time making your code safer and more robust, Scala is a very effective candidate. It's not the only candidate, but you should at least consider it.

saryant 13y ago
I'll echo all of this (minus scalaz, we don't use that). I'll give an example of the power of Scala's type system. When I first convinced one of our founders to give Scala a try, he used it to write the first pass of our analytics service. He'd never written Scala before but once it compiled, it ran correctly on the first try, that's the power of its type system.
- taeric 13y ago
  Not to be too big of an ass, but this could just be the skill of your founder. Or do you believe it is impossible to have compiling code that does not do as its author intended?
  - saryant 13y ago
    Obviously it's possible to write code that compiles while still not meeting requirements. My point is that the by leveraging the type system he was able to offload a lot of those checks to compile time rather than runtime.
  - lmm 13y ago
    It's not impossible, but it's harder in Scala. Actually the closest comparison I could make would be Python, where I had a similar experience - as soon as my code stopped producing errors, it was doing what I wanted it to (the difference being that the errors were at runtime rather than compile time). Whereas in Java and C and even ML I've written programs that compiled correctly but did something very different from what they were meant to.
- randomdata 13y ago
  Having never used Scala before, does its type system provide details about errors that other languages do not? Watching a compile fail because of an incorrect type is not something I have run into very often, if ever, in other languages that provide similar type systems. I mean mistakes can happen and if the type system can catch it for free, so to speak, that is great. I'm not about to argue that it is completely useless. But in terms of probabilities of what kind of bugs might be introduced, type errors seem to be on the low end. To infer that Scala's type system is powerful enough to catch the more common types of mistakes programmers make, that is quite an impressive claim. I am curious to know more.
  - jacobgreenleaf 13y ago
    In Haskell, and I assume Scala, you can name types of the same form, so I might say a TimeSeries is a list of floating point values. If I use that data type, you can't accidentally pass a different kind of list of floating points even though they're the same type.
bliti 13y ago
May you expand on the type of systems you are building with Scala? I have previous work experience in a multinational bank that ran Java or C# on everything.
dtawfik1 13y ago
I agree with everything above. At Vonjour we use Scala. From a business standpoint, our only reluctance was that hiring was going to be more difficult. However, we have received higher quality candidates that are eager to learn applying for our positions.
wwweston 13y ago
> That the author complains about having types rather than a simple map for keys shows a misunderstanding of what they are there for - the idea is to allow the compiler to prove at run-time what is valid code and what isn't. There's some evidence from what the author wrote he's aware of the benefits of type systems. The question he raises is whether the developers who wrote Spray modeled the problem domain well by choosing this particular set of types (his opinion is clearly no). > the author makes a strange comment that H-M 'enabled' Monads, and the comment is written in a way that implies that Scala does not have Monads. Given that the author immediately follows his "enabled" statement with the idea that monads can be used in a type-free language, I think it's most likely he means that H-M has been the ground where the use of monads has been largely developed/defined, not that monads can't be used in either Scala or even something with a considerably less expressive type system.
deleted 13y ago
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dbcfd 13y ago
> Coming to Scala from experience including C, Java and Haskell, I intially found Scala quite difficult. I think because it allows you to do OOP and FP, Scala becomes difficult since it is so easy to mix the styles. Similar to C and C++, this is very powerful, but also very dangerous. The main learning curve is programming in a way so you don't shoot yourself in the foot while using its flexibility.

saryant 13y ago

I'll echo all of this (minus scalaz, we don't use that). I'll give an example of the power of Scala's type system. When I first convinced one of our founders to give Scala a try, he used it to write the first pass of our analytics service. He'd never written Scala before but once it compiled, it ran correctly on the first try, that's the power of its type system.

taeric 13y ago
Not to be too big of an ass, but this could just be the skill of your founder. Or do you believe it is impossible to have compiling code that does not do as its author intended?
- saryant 13y ago
  Obviously it's possible to write code that compiles while still not meeting requirements. My point is that the by leveraging the type system he was able to offload a lot of those checks to compile time rather than runtime.
- lmm 13y ago
  It's not impossible, but it's harder in Scala. Actually the closest comparison I could make would be Python, where I had a similar experience - as soon as my code stopped producing errors, it was doing what I wanted it to (the difference being that the errors were at runtime rather than compile time). Whereas in Java and C and even ML I've written programs that compiled correctly but did something very different from what they were meant to.
randomdata 13y ago
Having never used Scala before, does its type system provide details about errors that other languages do not? Watching a compile fail because of an incorrect type is not something I have run into very often, if ever, in other languages that provide similar type systems. I mean mistakes can happen and if the type system can catch it for free, so to speak, that is great. I'm not about to argue that it is completely useless. But in terms of probabilities of what kind of bugs might be introduced, type errors seem to be on the low end. To infer that Scala's type system is powerful enough to catch the more common types of mistakes programmers make, that is quite an impressive claim. I am curious to know more.
- jacobgreenleaf 13y ago
  In Haskell, and I assume Scala, you can name types of the same form, so I might say a TimeSeries is a list of floating point values. If I use that data type, you can't accidentally pass a different kind of list of floating points even though they're the same type.

bliti 13y ago

May you expand on the type of systems you are building with Scala? I have previous work experience in a multinational bank that ran Java or C# on everything.

dtawfik1 13y ago

I agree with everything above. At Vonjour we use Scala. From a business standpoint, our only reluctance was that hiring was going to be more difficult. However, we have received higher quality candidates that are eager to learn applying for our positions.

wwweston 13y ago

> That the author complains about having types rather than a simple map for keys shows a misunderstanding of what they are there for - the idea is to allow the compiler to prove at run-time what is valid code and what isn't. There's some evidence from what the author wrote he's aware of the benefits of type systems. The question he raises is whether the developers who wrote Spray modeled the problem domain well by choosing this particular set of types (his opinion is clearly no). > the author makes a strange comment that H-M 'enabled' Monads, and the comment is written in a way that implies that Scala does not have Monads. Given that the author immediately follows his "enabled" statement with the idea that monads can be used in a type-free language, I think it's most likely he means that H-M has been the ground where the use of monads has been largely developed/defined, not that monads can't be used in either Scala or even something with a considerably less expressive type system.

deleted 13y ago

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dbcfd 13y ago

> Coming to Scala from experience including C, Java and Haskell, I intially found Scala quite difficult. I think because it allows you to do OOP and FP, Scala becomes difficult since it is so easy to mix the styles. Similar to C and C++, this is very powerful, but also very dangerous. The main learning curve is programming in a way so you don't shoot yourself in the foot while using its flexibility.