Type

• Numeric type: Int, Double (and Byte, Short, Char, Long, Float)
• Boolean type: with the values true and false
• String type
• Function type: ike Int => Int, (Int, Int) => Int

Expression

• Identifier: such as x, isGoodEnough
• Literal: like 0, 1.0, ”abc”
• Function application: like sqrt(x)
• Operator application: like -x, y + x
• Selection: like math.abs
• Conditional expression: like if (x < 0) -x else x
• Block: like { val x = math.abs(y) ; x * 2 }
• Anonymous function: like x => x + 1

Definition

• Function definition: like def square(x: Int) = x * x
• Value definition: like val y = square(2)

Parameter

• Call-by-value parameter, like (x: Int): is computed before calling the function
• Call-by-name parameter, like (y: => Double): is recomputed every time it is accessed