folone

### Keybase proof

I hereby claim:

  * I am folone on github.
  * I am folone (https://keybase.io/folone) on keybase.
  * I have a public key whose fingerprint is 3A57 D1D4 67F6 0189 3CB7  03D8 FA5C 9955 37B3 71EF

To claim this, I am signing this object:

folone

scala> trait Assoc[K] { type V ; val value: V }
defined trait Assoc

scala> def mkAssoc[K, V0](k: K, v: V0): Assoc[k.type] { type V = V0 } =
     | new Assoc[k.type] { type V = V0 ; val value = v }
mkAssoc: [K, V0](k: K, v: V0)Assoc[k.type]{type V = V0}

scala> def lookup[K](k: K)(implicit assoc: Assoc[k.type]): assoc.V = assoc.value
lookup: [K](k: K)(implicit assoc: Assoc[k.type])assoc.V

folone

> ++2.10.4
[info] Setting version to 2.10.4
[info] Set current project to wartremover (in build file:/Users/georgii/workspace/wartremover/)
> console
[info] Updating {file:/Users/georgii/workspace/wartremover/}wartremover...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Compiling 24 Scala sources to /Users/georgii/workspace/wartremover/target/scala-2.10/classes...
[info] Starting scala interpreter...
[info]

folone

scala> import play.api.libs.json._
import play.api.libs.json._

scala> case class Test[A: Writes](a: A)
defined class Test

scala> implicit def testWrites[A: Writes] = Json.writes[Test[A]]
<console>:12: error: No apply function found matching unapply parameters
       implicit def testWrites[A: Writes] = Json.writes[Test[A]]
                                                       ^

folone

def ackermann(m: Int, n: Int): Int = {
   (m, n) match {
     case (0, _)                   ⇒ n + 1
     case (m, 0) if m > 0          ⇒ ackermann(m - 1, 1)
     case (m, n) if m > 0 && n > 0 ⇒ ackermann(m - 1, ackermann(m, n - 1))
   }
 }
 
import scalaz._, Scalaz._, Free.{suspend ⇒ _, _}, Trampoline._
def ackermannTramp(m: Int, n: Int): Trampoline[Int] = {

folone

Scalaz
Symbol	Code	Ascii	Example
η	951	pure	1.η[List]
μ	03BC	join	List(List(1,2,3), nil, List(5,6,7)) μ
∅	2205	zero	∅[Int]
<∅>		empty	<∅>[Option, Int]
∙	2219	contramap	((_:String).length ∙ (_:Int).toString ∙ ((_:Int) + 6))(5)
∘	2218	map	(((_:Int) + 6) ∘ (_:Int).toString ∘ (_:String).length)(5)
∘∘

"map2":https://github.com/scalaz/scalaz/blob/master/core/src/main/scala/scalaz/MA.scala#L326

folone

> shapeless-examples/console
[warn] Credentials file /home/folone/.ivy2/.credentials does not exist
[warn] Binary version (2.10) for dependency org.scala-lang#scala-library;2.10.2
[warn] 	in com.chuusai#shapeless_2.10.2;2.0.0-SNAPSHOT differs from Scala binary version in project (2.10.2).
[warn] Binary version (2.10) for dependency org.scala-lang#scala-compiler;2.10.2
[warn] 	in com.chuusai#shapeless_2.10.2;2.0.0-SNAPSHOT differs from Scala binary version in project (2.10.2).
[info] Starting scala interpreter...
[info] 
Welcome to Scala version 2.10.2 (OpenJDK 64-Bit Server VM, Java 1.7.0_40).
Type in expressions to have them evaluated.

folone

final val BATCH_SIZE = (Runtime.getRuntime.freeMemory / 1024).toInt // kb per object should be enough, right?

def doStuff(m: MyType): Stream[MyType] = ??? // Costly operation
val s: Stream[MyType] = ???
s.grouped(BATCH_SIZE).toStream.flatMap(_.par flatMap doStuff)

folone

/*
 *  http://dysphoria.net/code/hindley-milner/HindleyMilner.scala
 *  Andrew Forrest
 *
 *  Implementation of basic polymorphic type-checking for a simple language.
 *  Based heavily on Nikita Borisov’s Perl implementation at
 *  http://web.archive.org/web/20050420002559/www.cs.berkeley.edu/~nikitab/courses/cs263/hm.html
 *  which in turn is based on the paper by Luca Cardelli at
 *  http://lucacardelli.name/Papers/BasicTypechecking.pdf
 *

folone

> effect/console
[warn] Credentials file /home/folone/.ivy2/.credentials does not exist
[warn] Credentials file /home/folone/.ivy2/.credentials does not exist
[info] Starting scala interpreter...
[info] 
Welcome to Scala version 2.9.2 (OpenJDK 64-Bit Server VM, Java 1.7.0_21).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scalaz._, Scalaz._, effect._