How to prompt the integer overflow in scala 3 REPL

% ./bin/scala -deprecation
Welcome to Scala 3.1.3 (18.0.1, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.

scala> Int.MaxValue+1
val res0: Int = -2147483648

I’m a newcomer to scala. Is there a solution to prompt me the integer overflow situation in scala 3 REPL, instead of getting the wrong calculation result.

1 Like

You can use the BigInt type to avoid overflows entirely. BigInt does not have a max or min value.

Otherwise, what you want can be accomplished by writing some code to detect the overflow. The book “Programming in Scala 5th Ed.” discusses this a bit:

You usually don’t want to trigger an actual exception in functional programming. Instead you can use an Option type. This is just one example, for absolute value function:

If you are new to Scala, I strongly recommend picking up this book! You can find answers to pretty much all your questions there.


Many thanks to your detailed, helpful explanations and recomendation. It seems that I get your points. BTW, I’m reading the the first half part of book “Programming in Scala 5th Ed.”.


You may find the methods that ends with Exact in the math package useful. They throw exceptions when calculations go bad due to overflow etc:

scala> math.addExact(Int.MaxValue, 1)
java.lang.ArithmeticException: integer overflow
  at java.base/java.lang.Math.addExact(
  at scala.math.package$.addExact(package.scala:400)
  ... 34 elided

scala> math. //press TAB
!=                addExact          getClass          rint
##                asInstanceOf      getExponent       round
->                asin              hashCode          scalb
==                atan              hypot             signum
BigDecimal        atan2             incrementExact    sin
BigInt            cbrt              isInstanceOf      sinh
E                 ceil              log               sqrt
Equiv             copySign          log10             subtractExact
Fractional        cos               log1p             tan
IEEEremainder     cosh              max               tanh
Integral          decrementExact    min               toDegrees
Numeric           ensuring          multiplyExact     toIntExact
Ordered           equals            negateExact       toRadians
Ordering          exp               nextAfter         toString
PartialOrdering   expm1             nextDown          ulp
Pi                floor             nextUp            →
ScalaNumber       floorDiv          nn
abs               floorMod          pow
acos              formatted         random