2.1 KiB
/* Set yourself up:
- Download Scala - http://www.scala-lang.org/downloads
- unzip/untar in your favourite location and put the bin subdir on the path
- Start a scala REPL by typing scala. You should see the prompt:
scala>
This is the so called REPL. You can run commands in the REPL. Let do just that: */
println(10) // prints the integer 10
println("Boo!") // printlns the string Boo!
// Evaluating a command gives you the type and value of the result
1 + 7
/* The above line results in:
scala> 1 + 7 res29: Int = 8
This means the result of evaluating 1 + 7 is an object of type Int with a value of 8
1+7 will give you the same result */
// Everything is an object, including a function type these in the repl:
7 // results in res30: Int = 7 (res30 is just a generated var name for the result)
// The next line gives you a function that takes an Int and returns it squared (x:Int) => x * x
// You can assign this function to an identifier, like this: val sq = (x:Int) => x * x
/* The above says this
sq: Int => Int =
Which means that this time we gave an explicit name to the value - sq is a function that take an Int and returns Int.
sq can be executed as follows: */
sq(10) // Gives you this: res33: Int = 100. The result is the Int with a value 100
// Data structures
val a = Array(1, 2, 3, 5, 8, 13) a(0) a(3) a(21) // Throws an exception
val m = Map("fork" -> "tenedor", "spoon" -> "cuchara", "knife" -> "cuchillo") m("fork") m("spoon") m("bottle") // Throws an exception
val safeM = m.withDefaultValue("no lo se") safeM("bottle")
val s = Set(1, 3, 7) s(0) s(1)
// Tuples
// Combinators
s.map(sq)
val sSquared = s. map(sq)
sSquared.filter(_ < 10)
sSquared.reduce (+)
// For comprehensions
for { n <- s } yield sq(n)
val nSquared2 = for { n <- s } yield sq(n)
for { n <- nSquared2 if n < 10 } yield n
for { n <- s; nSquared = n * n if nSquared < 10} yield nSquared
// Conditionals
val x = 10
if (x == 1) println("yeah") if (x == 10) println("yeah") if (x == 11) println("yeah")
// Object oriented features