In bash you can generate letter sequence easily as "{a..z}", for example
$ echo {a..z}
a b c d e f g h i j k l m n o p q r s t u v w x y z
How to do that in the fish shell instead?
Fish doesn't support ranges in brace expansion, only comma-separated values: {a,b,c}.
Thus, we are forced to search for a command capable of generating such sequence. For example, you can use Perl:
for c in (perl -e '$,="\n"; print ("a" .. "z")')
printf ">> %s\n" "$c"
end
where $, is the output field separator.
Output
>> a
>> b
...(skipped)
>> y
>> z
You may find this table useful.