(zsh brace expansion | seq) for character lists - how?

As this is still a top google result, an updated answer:

The current release supports bash style {c1..c2} where c1 and c2 are characters:

An expression of the form ‘{c1..c2}’, where c1 and c2 are single characters (which may be multibyte characters), is expanded to every character in the range from c1 to c2 in whatever character sequence is used internally. For characters with code points below 128 this is US ASCII (this is the only case most users will need). If any intervening character is not printable, appropriate quotation is used to render it printable. If the character sequence is reversed, the output is in reverse order, e.g. ‘{d..a}’ is substituted as ‘d c b a’.

This is definitely present in 5.0.7 onwards. I can't seem to find when this was introduced in the zsh release history, but the first archived version documenting it indicates it was introduced between July 2012 and November 2014.

zsh$ setopt BRACE_CCL
zsh$ echo {a-k}
a b c d e f g h i j k
zsh$ echo {1-9}
1 2 3 4 5 6 7 8 9

From ZSH Documentation:

BRACE_CCL

Expand expressions in braces which would not otherwise undergo brace expansion to a lexically ordered list of all the characters. See Brace Expansion.