+\//+\//+\//
is the same as
+ \( // ) + \( // ) + \( // )

The leading (unary) "+" is a no-op used to affect parsing in some situations, but it does nothing here.

\ is the reference taking operator. When used as a number, a reference returns the referenced memory address.

// is a match operator (m/.../).

It sums the memory addresses of the values returned by the three calls to the match op.

And since it returns a number, passing it to eval does nothing but return the same number.

I can't fathom find a use for it.

Update: Added a couple of details.

In reply to Re: eval'ing strange scalar by ikegami
in thread eval'ing strange scalar by hbm

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