IIRC (returned) boolean values in perl are either 1 or undef
Perl doesn't have "booleans". Function may return true or false values - it's not always defined which true or false value they return. The empty string is also often returned as a false value, and sometimes "0 but true" is returned. Or "0E0".

The manual page says:

The right operand is not evaluated while the operator is in the "false" state, and the left operand is not evaluated while the operator is in the "true" state. The precedence is a little lower than || and &&. The value returned is either the empty string for false, or a sequence number (beginning with 1) for true. The sequence number is reset for each range encountered. The final sequence number in a range has the string "E0" appended to it, which doesn’t affect its numeric value, but gives you something to search for if you want to exclude the endpoint. You can exclude the beginning point by waiting for the sequence number to be greater than 1.
Which explains it.

In reply to Re: Booleans from flip-flops by JavaFan
in thread Booleans from flip-flops by LanX

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