Opa is a functional language. One of its features is that functions are regular values, which means a function may be passed as a parameter or returned as a result. As such, they follow the same naming rules as any other value.
function f(x,y){ // function f with the two parameters x and y
x + y + 1
}
function int f(x,y){ // explicitly indicates the return type
x + y + 1
}You may notice that there is no return inside the body of a function. That's because Opa uses last expression return, which means the last expression of a function is the return value. For example:
function max(x,y){
if(x >= y) x else y
}If x is greater than or equal to y, then x is the last expression and x will be returned; if y is greater than x, then y is the last expression and y will be returned.