Entry tags:
could not figure out...
an example of a Set-endofunctor that does not preserve monomorphisms... any ideas?
Entry tags:
- covariance,
- list,
- scala,
- set
on variance, common sense in several short sentences
Why is type inference failing here?
scala> val xs = List(1, 2, 3, 3)
xs: List[Int] = List(1, 2, 3, 3)
scala> xs.toSet map(_*2)
<console>:9: error: missing parameter type for expanded function ((x$1) => x$1.$times(2))
xs.toSet map(_*2)