Scala for-comprehensions

gistfile1.scala

// The way Scala for-comprehensions work is that:

  for (x <- c) f(x)

// simply translates to:

  c.foreach(x => f(x))

// Likewise:

  for (x <- c) yield f(x)

// simply translates to:

  c.map(x => f(x))

// Something with a guard:

  for (x <- c if p(x)) yield f(x)

// translates* to:

  c.filter(x => p(x)).map(x => f(x))

// And a nested for:

  for (x1 <- c1; x2 <- c2) yield f(x1, x2)

// translates to:

  c1.flatMap(x1 => c2.map(x2 => f(x1, x2)))

// If the methods in the translation exist, you can use the for-syntax.












// *Note: Since Scala 2.8, the guard syntax:

  for (x <- c if p(x)) yield f(x)

// first tries to translate to this:

  c.withFilter(x => p(x)).map(x => f(x))

// and if the withFilter method doesn't exist, then it translates to this:

  c.filter(x => p(x)).map(x => f(x))