Let Expressions

With a let-expression you can declare a local variable. For example, the expression

let x := 10, y := x/2 in
  x + y
end;

evaluates to 15. Once again, all expressions evaluate to a value, in this case an integer. Thus you can write, for example,

1 + ( let x := 10, y := x/2 in
        x + y
      end );

which evaluates to 16.