Hello Chris,
thanks for the examples. They show that by adding anchors, the meaning
of regular expressions is no longer compositional. For example (^|a)
accepts the empty word only if no characters have been read yet. So
(^|a) =~ ""
does hold but
a(^|a) =~ "a"
does not hold although
a =~ "a"
does.
I deem compositionality an important property to compare the current
implementation with its specification. As, currently, I don't know how
to incorporate anchors without making a mess, I refrain from adding
them for the moment.
A more complicated use, perhaps as part of a crazy parser:
"(a(\n)?)(^|b)(c|$)"
That's a nice example and I don't know how to express this without
anchors.
Cheers,
Sebastian
--
Underestimating the novelty of the future is a time-honored tradition.
(D.G.)
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