paulp

// Thanks for inferring types which I can't even access, scala.
scala> def f[A, CC[X]](xs: CC[A]) = xs
warning: there were 1 feature warning(s); re-run with -feature for details
f: [A, CC[X]](xs: CC[A])CC[A]

scala> f(scala.collection.immutable.BitSet(1))
res0: scala.collection.AbstractSet[Int] = BitSet(1)

scala> var x: scala.collection.AbstractSet[Int] = res0
<console>:9: error: class AbstractSet in package collection cannot be accessed in package collection

paulp

/** This should properly be a 'pos' test - all of it should compile.
 *  As usual it's in neg so as to alert the media if the behavior changes.
 */

package p1 {
  trait Foo[+A]
  trait Bar[+A] extends Foo[A]
  class Good() extends Foo[Int] // directly inherits Foo[Int]
  class Bad() extends Bar[Int]  // indirectly inherits Foo[Int]

paulp

 65138 Paul Phillips
 25821 Martin Odersky
 19246 Eugene Burmako
 15572 Aleksandar Prokopec
 10850 Miguel Garcia
  9197 Jason Zaugg
  7652 Stéphane Micheloud
  6952 Iulian Dragos
  5807 Adriaan Moors
  3367 Den Shabalin

paulp

[info] Compiling 10 Scala sources to /s/gll-combinators/target/scala-2.11.0-M8/test-classes...
[error] type mismatch;
[error]  found   : => Any
[error]  required: AnyRef
[error] Note that <byname> extends Any, not AnyRef.
[error] Such types can participate in value classes, but instances
[error] cannot appear in singleton types or in reference comparisons.
[error] one error found
[error] (test:compile) Compilation failed
[error] Total time: 41 s, completed Feb 4, 2014 8:11:22 AM

paulp

    "compute FIRST for binary alternatives" in check { (left: String, right: String) =>
      import com.codecommit.util._
      
      val leftFirst = if (left.length == 0) Set[Char]() else Set(left charAt 0)
      val rightFirst = if (right.length == 0) Set[Char]() else Set(right charAt 0)
      
      if (leftFirst.size == 0 || rightFirst.size == 0)
        (left | right).first eq UniversalCharSet
      else
        (left | right).first == (leftFirst ++ rightFirst)

paulp

import com.codecommit.gll._
import org.specs2.ScalaCheck
import org.specs2.mutable._

trait Foo extends Specification with Parsers with ScalaCheck {
  check { (left: String, right: String) =>
    // import java.lang.String
    if (false)
      null == null
    else

paulp

trait Foo
class Ev[T]
case class Bar[A](xs: Ev[A], f: A => Unit) extends Foo

object Test {
  def main(args: Array[String]) {
    val foo: Foo = new Bar(new Ev[Int], println(_: Int))

    // This is disallowed.
    // foo match { case x: Bar[a] => x.f(x.xs) }

paulp

object Nats {
  sealed trait Nat {
    type Prev <: Nat { type Succ = Nat.this.type }
    type Succ <: Nat { type Prev = Nat.this.type }
  }
  object Zero extends Nat

  type _0 = Zero.type
  type _1 = _0#Succ
  type _2 = _1#Succ

paulp

// zip two lists, call map, function types inferred
scala> SafeList(1, 2, 3, 4) zip SafeList[Double](1, 2, 3, 4) map (_ + _)
res0: psp.core.Foreach[Double] = 2.0 :: 4.0 :: 6.0 :: 8.0 :: Nil

// zip three lists, call map, function types inferred
scala> SafeList(1, 2, 3, 4) zip SafeList[Double](1, 2, 3, 4) zip SafeList[Long](1, 2, 3, 4) map (_ + _ + _)
res1: psp.core.Foreach[Double] = 3.0 :: 6.0 :: 9.0 :: 12.0 :: Nil

paulp

package p {
  trait N { type Name ; def make(): Name }
  trait N1 extends N { class Name ; def make(): Name = new Name }
  trait N2 extends N { class Name }

  object g extends App with N1 with N2 {
    val x = (this: N2).make()
    // java.lang.ClassCastException: p.N1$Name cannot be cast to p.N2$Name
  }
}