Ticket #0001317

Type	Issue	Status	problem	Date	4-Nov-2009 20:30
Version	alpha 94	Category	Syntax	Submitted by	meijeru
Platform	All	Severity	minor	Priority	normal

Summary	] is not allowed as first character in tag, [ and ( ) are
Description	This seems somewhat arbitrary. All four signs are allowed in subsequent positions in tag literals.
Example code	>> type? <[> == tag! >> type? <]> ** Syntax error: missing "[" at "end-of-block" >> type? <a]> == tag! >> type? <(> == tag! >> type? <)> == tag!

Assigned to	n/a	Fixed in	-	Last Update	30-Mar-2015 00:49

Comments
(0003221) BrianH 19-Feb-2012 17:45	Here is how it was in R2: >> [>] == [>] >> [<] Syntax Error: Invalid tag -- < Near: (line 1) [<] You couldn't even avoid it by putting spaces around the < because this would inevitably happen: >> mold [ < ] == "[<]" ; Note that MOLD generates the non-loadable syntax. This was bad, so we changed it to this syntax interpretation in R3: >> [>] == [>] >> [<] == [<] If you allow ] as the first character in a tag, you disallow the word < as the last word in a block. [<] is useful in some code-generation code and some dialects, while <]> doesn't seem to be commonly used at all, so it's a good tradeoff.
(0004617) MarkI 30-Mar-2015 00:49	I'd love to hear the reasoning behind why this was not also changed at the same time: >> [ ( < ) ] == [(<)] >> [(<)] Syntax error: invalid "tag" -- "<" Near: (line 1) [(<)] Seems MOLD still generates non-loadable syntax in this very similar case.

Comments

(0003221)
BrianH
19-Feb-2012 17:45

Here is how it was in R2:
>> [>]
== [>]
>> [<]
** Syntax Error: Invalid tag -- <
** Near: (line 1) [<]

You couldn't even avoid it by putting spaces around the < because this would inevitably happen:
>> mold [ < ]
== "[<]" ; Note that MOLD generates the non-loadable syntax.

This was bad, so we changed it to this syntax interpretation in R3:
>> [>]
== [>]
>> [<]
== [<]

If you allow ] as the first character in a tag, you disallow the word < as the last word in a block. [<] is useful in some code-generation code and some dialects, while <]> doesn't seem to be commonly used at all, so it's a good tradeoff.

(0004617)
MarkI
30-Mar-2015 00:49

I'd love to hear the reasoning behind why this was not also changed at the same time:
>> [ ( < ) ]
== [(<)]
>> [(<)]
** Syntax error: invalid "tag" -- "<"
** Near: (line 1) [(<)]

Seems MOLD still generates non-loadable syntax in this very similar case.

Date	User	Field	Action	Change
30-Mar-2015 00:49	MarkI	Comment : 0004617	Added	-
19-Feb-2012 17:52	BrianH	Status	Modified	reviewed => problem
19-Feb-2012 17:51	BrianH	Comment : 0003221	Modified	-
19-Feb-2012 17:45	BrianH	Comment : 0003221	Added	-
24-Nov-2009 04:39	carl	Status	Modified	submitted => reviewed
4-Nov-2009 20:45	meijeru	Version	Modified	alpha 95 => alpha 94
4-Nov-2009 20:30	meijeru	Summary	Modified	] is not allowed as first character of in tag, [ and ( ) are => ] is not allowed as first character in tag, [ and ( ) are
4-Nov-2009 20:30	meijeru	Code	Modified	-
4-Nov-2009 20:30	meijeru	Ticket	Added	-