Scala exercises

scala-exercises.scala

Exercises
=========

Scala intro
-----------

1. Check if a string has balanced parentheses.

2. There is an inventory of items in a shop costing 615, 452, 356, 184, 172, 156, 135, 115, 78, 56, 48 lv. Find at least one way to spend exactly 992 lv. How about exactly 796 lv.?

Functional programming with Scala
---------------------------------

1. Implement a tail-recursive function "size" that takes a list and returns its length
2. Implement tail-recursive "filter" and "map" that take a list and a function as parameters
3. Implement "map" and "filter" in terms of "foldLeft"
Extra: Try to implement previous homework solutions recursively
Extra: Try to implement previous homework solutions with for comprehensions in terms of flatMap/filter/map

ADTs
----

1. Using the Option API (http://www.scala-lang.org/api/current/scala/Option.html) rewrite the following pattern matches with higher-order functions:

option match {
 case None => None
 case Some(x) => foo(x)
}

option match {
 case None => None
 case Some(x) => x
}

option match {
 case None => None
 case Some(x) => Some(foo(x))
}

option match {
 case None => {}
 case Some(x) => foo(x)
}

option match {
 case None => false
 case Some(_) => true
}

option match {
 case None => true
 case Some(_) => false
}

option match {
 case None => true
 case Some(x) => foo(x)
}

option match {
 case None => false
 case Some(x) => foo(x)
}

option match {
 case None => foo
 case Some(x) => Some(x)
}

option match {
 case None => foo
 case Some(x) => x
}

option match {
 case None => Nil
 case Some(x) => x :: Nil
}