my assumption was that the lambda in getOrElse should need t

Question

my assumption was that the lambda in getOrElse should need to return Heros object as default value

Shawn · Answer

unsure if you ve realized yet but this is why `age1` is typed as `Any` instead of `Hero` you re supplying an Int as a default for a `get` that returns `Hero `

Shawn · Answer

you re conflating steps getting an object out of the map and accessing a property in that property

Shawn · Answer

you re only doing the former

Shawn · Answer

this is still being statically checked by the way but the type system inference sorta relies on you knowing what you re doing

amit · Answer

Thanks < Shawn> for reply but getOrElse accepts lambda of type gt V where V should ideally be match with value type present in Map lt K V gt so effectively getOrElse should accepts gt Heros but it is also accepting gt Int

amit · Answer

I am a beginner so I am little bit confused here but can be trivial question

amit · Answer

Can you please direct me to any resource which talks more about this

Shawn · Answer

Basically the short answer is that this is happening due to variance specifically because the signature of the map interface isn t `Map lt K V gt ` it s `Map lt K out V gt ` When calling ` getOrElse ` with a lambda that returns a type that isn t `V` or a subtype the type system infers that you intend to operate on a map where `K` is the same but `V` is now a supertype of the original map s `V` since it s a covariant type parameter

Shawn · Answer

in this case `V` is resolved to be the only thing it can be which is `Any`

Shawn · Answer

if you try calling getOrElse with explicit type parameters like this ```mapByName getOrElse lt String Any gt unknown 0 ``` IntelliJ will gray out the parameters and indicate that they are redundant since this is what the type system has already resolved

Shawn · Answer

you can also see this in action by just assigning the map to a valid supertype ```val superMap Map lt String Any gt = mapByName```

Shawn · Answer

if you explicitly annotate `age1` as `Hero` or change the invocation to ` getOrDefault lt String Hero gt ` then the type checker will raise an error

amit · Answer

yes that I tried thanks for the information slightly smiling face

Shawn · Answer

amit · Answer

thanks Need to go through it much to digest