// Swift 4 builtin data types:
//
// * Int or UInt (Int32, Int64, UInt32, UInt64)
// * Float
// * Double
// * Bool
// * String
// * Character
// * Optional − a variable that can hold either a value or no value.
// * Tuples
// 
// | -------|-------------------|-----------------------------------------------|
// | Type   |  Typical Bit Width|  Typical Range                                |
// | -------|-------------------|-----------------------------------------------|
// | Int8   |  1byte            |  -127 to 127                                  |
// | UInt8  |  1byte            |  0 to 255                                     |
// | Int32  |  4bytes           |  -2147483648 to 2147483647                    |
// | UInt32 |  4bytes           |  0 to 4294967295                              |
// | Int64  |  8bytes           |  -9223372036854775808 to 9223372036854775807  |
// | UInt64 |  8bytes           |  0 to 18446744073709551615                    |
// | Float  |  4bytes           |  1.2E-38 to 3.4E+38 (~6 digits)               |
// | Double |  8bytes           |  2.3E-308 to 1.7E+308 (~15 digits)            |
// | -------|-------------------|-----------------------------------------------|

// Type Aliases:
//
    typealias Feet = Int
    var distance: Feet = 100
    print(distance)
    
// Type inference:
//
// varA is inferred to be of type Int
    var varA = 42
    print(varA)
//
// varB is inferred to be of type Double
    var varB = 3.14159
    print(varB)
//
// varC is also inferred to be of type Double
    var varC = 3 + 0.14159
    print(varC)