Scala - Sum of positive Ints being negative

i had hard time finding bug being caused due large sum of positive ints being greater integer.max_value.

my question is: why:

val a:int = integer.max_value + 2

-> = -2147483648 returns negative number, opposed giving overflow exception doing:

val b:int =999999999999999999

-> error: integer number large

why not throwing exception standard?

adding checks costs performance , code rely on how overflows work.

if don't want overflow java 8 has solution:

math.addexact(left, right);

JVParth