How does scala infers the type of a variable?

Question

I am always fascinated to see how scala always infers the type correctly . How scala does it?

scala> val num = 5

num: Int = 5



scala> val num = "5"

num: String = 5

I know it might be a very stupid question to ask here but i don't know the answer.
Please enlighten me.
Thanks!

Answer 1

There are several methods for inferencing the type of a variable. Mainly using those called inference rules based in logic theory.

There are plenty of papers explaining the theory behind. Here I put a good example (with Scala ;) )

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