Hi all,
$ echo {a..zz}
{a..zz}
Right; the sequence is not well-formed according, and so this is not brace
syntax; the syntax stays intact as verbatim text, braces and all.
But:
$ echo {a..{z,y}}
a..z a..y
Is this documented? I would expect it to produce
{a..z} {a..y}
on the hypothesis that the outer brace is not well-formed, and
therefore literal, but the inner brace is active, like any
valid brace in the middle of literal text. I.e. we have
"alpha{brace}omega", where alpha is "{a.." and omega is "}".
If we strip the braces, that means we have recognized the syntax
for special processing, but then it is not evident in the
a..z a..y output how it relates to sequence expansion.
I came across this because the recent discussion in this list prompted
me to go looking into my own brace expansion implementation, which
I recently extended into supporting sequences.
It has the expected behavior:
1> (sys:brace-expand "{a..{z,y}}")
("{a..z}" "{a..y}")
I was just "comparing notes" on some exotic cases like this against
Bash, and noticed this.
(An interesting way to treat this case would be to allow the inner
element expansion to produce multiple sequence expansions,
which are then processed; i.e. as if we took the resulting
{a..z} and {a..y} shown in my implementation, and then "activated"
the braces.)
Cheers ...
