Why does Scala choose to have the types after the variable names?

Question

In Scala variables are declared like:

var stockPrice: Double = 100. 

Where the type (Double) follows the identifier (stockPrice). Traditionally in imperative languages such as C, Java, C#, the type name precedes the identifier.

double stock_price = 100.0; 

Is it purely a matter of taste, or does having the type name in the end help the compiler in any way? Go also has the same style.

Answer 1

Kevin's got it right. The main observation is that the "type name" syntax works great as long as types are short keywords such as int or float:

int x = 1 float d = 0.0 

For the price of one you get two pieces of information: "A new definition starts here", and "here's the (result) type of the definition". But we are way past the area of simple primitive types nowadays. If you write

HashMap<Shape, Pair<String, String>> shapeInfo = makeInfo() 

the most important part of what you define (the name) is buried behind the type expression. Compare with

val shapeInfo: HashMap[Shape, (String, String)] = makeInfo() 

It says clearly

• We define a value here, not a variable or method (val)
• The name of the thing we define is shapeInfo
• If you care about it, here's the type (HashMap[...])