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Choosing Scala

teaching.software-carpentry.org

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Re: Choosing Scala

#51

Post by cryptos »

mark242 wrote: post #39
leokun wrote: post #32

I don't come from a CS background, but I have been programming professionally many years and recently got started with Scala. I had tried Go before and I like Go. I also really like Scala. Scala requires much more work to learn than Go. I don't think I ever ventured out much from the offical Go documentation, the spec and effective Go and the library documentation to learn Go. With Scala I've already bought 3 books,…

Having worked with Scala for the past almost two years, I can tell you this: you're missing out by not using IntelliJ. It is a huge timesaver, not just from the code completion or the inspections, but also by being able to fire up FSC outside of IntelliJ and have your code recompile very, very quickly when you make changes. The one thing that IntelliJ doesn't do very well yet is work with sbt. It works, sure, but the…

IntelliJ IDEA 13 will have a real SBT integration.

Re: Choosing Scala

#52

Post by microtonal »

leokun wrote: post #32

I don't come from a CS background, but I have been programming professionally many years and recently got started with Scala. I had tried Go before and I like Go. I also really like Scala. Scala requires much more work to learn than Go. I don't think I ever ventured out much from the offical Go documentation, the spec and effective Go and the library documentation to learn Go. With Scala I've already bought 3 books,…

Scala requires much more work to learn than Go.

Although I like Haskell and FP, this is one of the reasons that I have been very hesitant using Scala in my previous or current position, although both were Java/JVM-heavy. Using Scala has the implication that some of my colleagues have to learn it as well, and learning FP and Scala well can be a multi-month or multi-year project.

With a language such as Kotlin, one can scrap much of the Java boilerplate, while most of it is very easy to pick up for a Java programmer in a few days or weeks.

That said, Typesafe are doing great work! I use and love Akka and it works great in Java as well (if you don't need to compose futures to much :^)).

Re: Choosing Scala

#53

Post by Sharlin »

agentultra wrote: post #30
jmgao wrote: post #7

Earlier quoted context omitted.

It's inherited from Java, where adding something and a string will implicitly convert the something into a string. The C++ behavior is notably worse, though: "5" + 5 in C++ is undefined behavior, and will give you a pointer to some mystery data.

The example is merely illustration and not the recommended practice for writing C++! (Can you imagine?) I only meant to illustrate that even in C++ where types have a different meaning I will get a warning with a decent compiler. In either case the expression in both languages garners a silly result. However Scala is happy with the result and reports nothing wrong with it (not even a warning). I was just surprised is…

How is the result in Scala/Java silly? I'd say it's perfectly intuitive to most people that you can concatenate non-strings to strings using that syntax, via an implicit conversion of the non-string operand. You could do the same thing in C++ with operator overloading, and the unnecessary difficulty of building strings in C++ is probably one of the pet peeves of most people, and certainly something hard to explain to beginners (who will probably try "5" + 5 and be very very confused when the result is garbage instead of "55").

Re: Choosing Scala

#54

Post by lmm »

leokun wrote: post #32

I don't come from a CS background, but I have been programming professionally many years and recently got started with Scala. I had tried Go before and I like Go. I also really like Scala. Scala requires much more work to learn than Go. I don't think I ever ventured out much from the offical Go documentation, the spec and effective Go and the library documentation to learn Go. With Scala I've already bought 3 books,…

Did you know Java before? I can understand not being able to use Scalaz (heck, after three years of scala there are parts of Scalaz I wouldn't go to yet), or read other people's scala code, but my experience is that you can start writing scala to do useful things in two minutes, because you can write java (or C#) and it will work.

(Advice for understanding scalaz: look at the type signatures. Try and implement a function with that type signature yourself. In fact, the first few times I find it's best to write the thing without using scalaz myself, then notice that part of it has a type signature that matches a method in scalaz, and then replace that with the scalaz method.)

Re: Choosing Scala

#55

Post by lmm »

codygman wrote: post #27
CookWithMe wrote: post #20

Earlier quoted context omitted.

scala> "5" + 5 res0: java.lang.String = 55 Don't use print in the REPL... > Python gives me a TypeError. And so does Common Lisp. I was expecting the same from Scala scala> val i:Int = "5" + 5 :7: error: type mismatch; found : java.lang.String required: Int val i:Int = "5" + 5 ^ You can easily get a compiler error, if you enforce the type. The inheritance of Javas "I'll call .toString on anything" is definitely not s…

Isn't this something that type inference should catch though?

The type of "5" + 5 is inferred to be String. If you pass it to print(), which takes a String, that's not an error, and printing "55" is presumably what you meant to happen. If you tried to pass it to a method expecting an integer, you'd get an error.

Re: Choosing Scala

#56

Post by klibertp »

mercurial wrote: post #47
noahmarc wrote: post #29

Earlier quoted context omitted.

Thanks for joining the discussion. Just want to say I'm working through the the videos for your coursera course ( https://www.coursera.org/course/progfun ) and, in addition to being a great introduction to Scala, it's changing how I approach other functional languages like JavaScript and R

At most JavaScript is an imperative language with functional flavour

Try LiveScript: http://livescript.net/

JS semantics are those of a functional-oop language. It lacks a few standard functions (LiveScript has prelude-ls) and a ton of syntactic support for things. Once these are in place, you can write the code which looks and feels like Ocaml.

For example, moment.js function is `moment(dateString, formatString)`. In LiveScript I used it as:

     parseDate = (flip moment) "DD/MM/YYYY"
Now tell me that this doesn't look like functional code :)

(The only really lacking feature in JS is of course TCO, but then Clojure, so yeah, let's just trampoline everything.)

Re: Choosing Scala

#57

Post by room271 »

I use Scala in my job and, though I never formally studied CS, I would be concerned at using it for an introductory course at university.

Scala is fundamentally a pragmatic language - it is about compromise between functional purity and JVM/Java-style (OOP-based) mutation. As such, it's hard to really identify the distinctive features of either because Scala is so liberal in what it allows.

I wonder whether students would be better off learning something like Haskell along with (e.g.) Python or Java. And of course a Lisp of some kind(!).

Re: Choosing Scala

#58

Post by Fiadliel »

chilldream wrote: post #45
hrjet wrote: post #43

Earlier quoted context omitted.

> it's an overload and a typecast. No, in Scala there is no typecast in that example. Everything is an object in Scala and the + method in String class accepts an object as parameter. There is some auto-boxing happening under the hoods but that is not type-casting.

You start with an integer and end up with a string. The intermediate steps required to get from one to the other aren't particularly relevant to the point I was making.

The string concatenation API for Java IS terrible, but see modersky's post for the reasoning.

Just don't mistake a bad API for some kind of belief that Scala in general idly converts between types. The weakest point is APIs that use methods defined in java.lang.Object (e.g. toString and equals); they can universally use these methods without restricting the type.

Note that if you define a type as a knowledge of what actions can be performed on an object, then no type safety has been lost; toString() is universally available, though it may not do exactly what you want.

Re: Choosing Scala

#59

Post by parasubvert »

yelnatz wrote: post #41
sampo wrote: post #26

Earlier quoted context omitted.

> "I'm glad that they didn't go with Java" That School (Aalto University) has used Java as a first year language for quite some time. Then they switched to Python (I think), and then to Scala. Before Java, it was Scheme. Before Scheme, I don't know.

My university switched from Java to Scheme (Racket) for their first year language. I'm not sure why they're trying to scare the poor first years away.

I think Scheme is a good second year language, which is really when The Fear should set in among the uncommitted.

Re: Choosing Scala

#60

Post by leokun »

bad_user wrote: post #49
leokun wrote: post #32

I don't come from a CS background, but I have been programming professionally many years and recently got started with Scala. I had tried Go before and I like Go. I also really like Scala. Scala requires much more work to learn than Go. I don't think I ever ventured out much from the offical Go documentation, the spec and effective Go and the library documentation to learn Go. With Scala I've already bought 3 books,…

> With Scala I've already bought 3 books, and have bookmarked nearly 100 sites. I've also written a blog post about learning resources. Maybe it helps you: https://www.bionicspirit.com/blog/2013/05/13/getting-started... As a word of warning, don't use Scalaz while in the learning process. It's a pretty cool library, but I've been developing with Scala for the past 2 years already and personally I've never felt the ne…

Thanks for pointing me to your blog post, that's very useful. The points about what are great about Scala also very interesting. I really like scala, despite the hard work it takes to get going.
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