in perl(v5.14.2), why is map{+0,0}() correct but map{0,0}() not? [duplicate]

Question

It seems that perl treat {+0,0} as a BLOCK and {0,0} an EXPR But why? Is that a special provision?

If I want to make sure that the {} is an anonymous hash whatever the braces contain, do I have to put a `+' before {} ?

thanks.

Answer 1

Why? Because it could be either, and the parser doesn't look far enough ahead to know for sure by the time it needs to decide.

Do you have to put a '+' before {} to have it be treated as an anonymous hash constructor regardless of the contents of the {}? Yes.