Re: [scala-language] Units of Measurement — Scala Macros to the rescue?

On Feb 5, 2012, at 10:45 AM, Miles Sabin wrote:
> What Rex is saying (quite reasonably IMO) is that whatever the X in
> "equality wrt to X" it should at least be an equivalence relation, ie.
> reflexive, symmetric and transitive.

Shouldn't === use the equivalence relation for the LUB of the argument types.

Given

a: A
b: B
C <: A
C <: B
D <: C

with

eqD being the equivalence relation wrt D
eqC being the equivalence relation wrt C

then you should have

eqD ⊆ eqC

which gives

eqD(a,b) => eqC(a,b)

all by the substitutability principle.

[scala-language] Units of Measurement — Scala Macros to the rescue?

classpath setByUser in Scala 2.10

Hi all,

finally I ported ScalaLab to Scala 2.10.

The reason behind the "object Scala not found"
message that I took before,
is the new
  "setByUser" flag
that defaults to false and requires to set it to set to true,
in order to enable configuration of the classpath of the compiler in
2.10.

It seems to me somewhat tricky to find it !!

Best Regards

Stergios

Re: Re: Re: Re: Re:

InfoQ talk about Type Providers in F# 3.0

Type classes and implicits

Hi all,

I'm playing with type classes and implicits and don't understand why
both of the println lines below produce the compiler error:

could not find implicit value for evidence parameter of type
GenericBased[scala.collection.immutable.Set]

I surely understand the message but I don't understand why the mentioned
type could not be found. Why can't the compiler relate a Set with a
Traversable? Any thoughts?

(I need the GenericBasedWrapper only, as Scala doesn't support some kind
of implicit infix functions).

My code:
=========
import scala.collection.parallel.ParIterable

object Test extends App
{
    implicit val traversableBased = TraversableBased
    implicit val parallelBased = ParallelBased

    implicit def toGenericBasedWrapper[A, C[A] : GenericBased](source:
C[A]): GenericBasedWrapper[A, C] = new GenericBasedWrapper[A, C](source)

    println(Set[Int](1, 2, 3).doSomething((set: Set[Int]) => set.map(a
=> a + 1)))
    println(Set[Int](1, 2, 3).doSomething(set => set.map(a => a + 1)))
}

class GenericBased[+C[_]]
{
    def doSomething[A](source: C[A], f: C[A] => C[A]): C[A] = f(source)
}

class GenericBasedWrapper[A, +C[_]: GenericBased](source: C[A])
{
    def doSomething(f: C[A] => C[A]): C[A] =
implicitly[GenericBased[C]].doSomething[A](source, f)
}

object TraversableBased extends GenericBased[Traversable]
object ParallelBased extends GenericBased[ParIterable]

--

-- 
Best Regards

Ka Ter

usejavacp = true with Scala 2.10

Hi all,

I have a problem porting ScalaLab with Scala 2.10: 

when I use in Settings the  usejavacp = true
it works within Netbeans correctly,
but when I run the executable standalone,
it outputs the error: "object scala not found"

In Scala 2.8 and Scala 2.9 the same code runs without problem,
without setting usejavacp=true

Can somebody identify what happens?

Regards
Stergios

Regression in Scala 2.10 concerning self types

java.lang.NoClassDefFoundError scala on JVM

Reorganization of SIPs site, please update your forks

Hi all, 

(cross-posted from scala-sips)

We've done a bit of reorganizing on the SIPs site. The content and URLs are all exactly the same, but any
existing forks of the repo need to be updated to use: http://github.com/scala/scala.github.com.

Cheers, 
Heather

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