hamishdickson

/*
 * here is a cool thing @Astrac did
 *
 * lifts `A => F[B]` to `F[A => B]`, where `F` has a Comonad and an applicative
 */
def lift[F[_], A, B](f: A => F[B])(implicit cm: Comonad[F], ap: Applicative[F]): F[A => B] = ap.pure(a => f(a).extract)

hamishdickson

final case class Cofree[F[_], A](head: A, tail: F[Cofree[F,A]])

val fibs: Cofree[Eval, Int] = {
  def unfold(p1: Int, p2: Int): Cofree[Eval, Int] =
    Cofree(p1 + p2, Eval.later(unfold(p2, p1 + p2)))

  unfold(0, 1)
}

scala> fibs.head

hamishdickson

[info] Loading global plugins from /Users/hamishdickson/.sbt/0.13/plugins
[info] Updating {file:/Users/hamishdickson/.sbt/0.13/plugins/}global-plugins...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to catsSandbox (in build file:/Users/hamishdickson/Workspace/catsSandbox/)
[info] Starting scala interpreter...
[info]
Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_101).
Type in expressions for evaluation. Or try :help.

hamishdickson

scala> trait Foo[T] {
     | type A
     | def woozle(a: T): A
     | }
defined trait Foo

scala> implicit val bar = new Foo[Int] {
     | type A = String
     | def woozle(a: Int): A = s"hamish has had $a cakes today"
     | }

hamishdickson

scala> trait Foo[T] {
     | type A
     | def woozle(a: T): A
     | }
defined trait Foo

scala> implicit val bar = new Foo[Int] {
     | type A = String
     | def woozle(a: Int): A = s"num: $a"
     | }

hamishdickson

SIP SLIP meeting October 2015

Welcomes and apologies

• Welcome to @sjrd who joins us
• @odersky, @jsuereth, @dickwall and @SethTisue are all there
• @dickwall gloats about his holiday
• @Eran has the flu
• @heathermiller is "otherwise engaged"

hamishdickson

$ ghci -XNoMonomorphismRestriction
GHCi, version 7.10.2: http://www.haskell.org/ghc/  :? for help
Prelude>

hamishdickson

public Test {
  
    public void testMyThing() {
        MyClass myClass = new MyClass();
        
        Method method = myClass.getClass().getDeclaredMethod("setId", ArgTypeIfAny.class);
        privateStringMethod.setAccessible(true);
        
        method.invoke(myClass, args);
    }

hamishdickson

select(FruitTable.name, FruitTable.juiciness)
  .from(FruitTable)
  .where(FruitTable.juiciness >= 8)
  .orderBy(FruitTable.juiciness.desc)
  .fetchAll(fruitExtractor)

hamishdickson

object DeleteExamples extends App with DatabaseExample {
  InsertExamples.insertAll

  val deleteStatement =
    delete
      .from(FruitTable)
      .where(FruitTable.name === """Banana""")

  // try again to run the delete statement in a transaction
  database.withTransaction {