/<a foo bar>/ parses, but is that a valid syntax?

[zoffixznet]

Stumbled on this calling form that seems to parse the space separated stuff as regexes and then calls the token with ForeignCode that appears to be some regex stuff.

Is this valid syntax for some feature or is this an error that should be throwing?

16:42 	camelia 	rakudo-moar 8e1366e7a: OUTPUT: «ForeignCode.new␤»
16:42 	Zoffix 	m: grammar { token TOP { <a foobarber> }; method a($_) { .perl.say; exit } }.parse: ""
16:42 	camelia 	rakudo-moar 8e1366e7a: OUTPUT: «ForeignCode.new␤»
16:42 	Zoffix 	m: grammar { token TOP { <a foobarber zef> }; method a($_) { .perl.say; exit } }.parse: ""
16:42 	camelia 	rakudo-moar 8e1366e7a: OUTPUT: «Potential difficulties:␤    Space is not significant here; please use quotes or :s (:sigspace) modifier (or, to suppress this warning, omit the space, or otherwise change the spacing)␤    at <tmp>:1␤    ------> 3grammar { token TOP { <a foobarb…»

16:46 	Zoffix 	m: say grammar { token TOP { <a alpha> }; token a($_) { . { say $_(Match.^lookup("!cursor_init")(Match, "abc", :0c)) } } }.parse: "abc"
16:46 	camelia 	rakudo-moar 8e1366e7a: OUTPUT: «#<failed match>␤Nil␤»

[jnthn]

Yes, it is the syntax that lets us parse <before abc> and similar. Unlike with <foo: ...> and <foo(...)>, where the args are parsed by the MAIN language, the <foo ...> form parses the rest of the assertion using the regex language, wraps it in a closure, and passes it to foo. Thus it's a general syntax for higher-order regex operators - which is just what before/after are.

[zoffixznet]

Thanks!