Generics in scala for addition - 


class calculator[a:numeric]{    var x:a = _;    def sum() : = x+x;  //error:   }

compiler errors:

  1. can't resolve + symbol on a
  2. type mismatch; expected: string, actual: a

class calculator[a: numeric]{ ... }

is syntax sugar for

class calculator[a](implicit n: numeric[a]){ ... }

if in the docs numeric you'll find implicit def mkorderingops uses "enrich library" pattern add math operators + a type.

you need import mkorderingops instance of numeric.

keeping current class signature, can use implicitly[numeric[a]] instance. putting together, get:

class calculator[a: numeric] {   private val n = implicitly[numeric[a]]   import n._ // mkorderingops included here        var a: = _   def sum = + // + coming mkorderingops conversion }

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