List() command: extends capabilities

I propose to extend command list() by adding various new sub-commands.

Before starting implementation, I need feed-back about these propositions. I sorted them by importance (most important/useful first) from my point of view.

• SUBLIST: to extract a sub-list from a list.

# list (SUBLIST <list> <start> <length> <output variable>)
set (mylist a b c d)
list (SUBLIST mylist 1 -1 sublist)
# result: b c d

• CONCAT: To concatenate a PREFIX or a SUFFIX to each list's elements.

# list (CONCAT <list> <PREFIX|SUFFIX> <value>)
set (dirs dir1 dir2)
list (CONCAT dirs PREFIX "/root/")
# result: /root/dir1 /root/dir2

• INSERT: To insert, BEFORE or AFTER each list's elements a new value.

# list (INSERT <list> <BEFORE|AFTER> <value>)
set (defines DEF1 DEF2)
list (INSERT defines BEFORE "-D")
# result: -D DEF1 -D DEF2

• REPLACE_AT, REPLACE_ITEM, REPLACE: To replace elements with new value.

# list (REPLACE_AT <list> <index> [<index> ...] <new value>)
# list (REPLACE_ITEM <list> <value> [<value> ...] <new value>)
# list (REPLACE <list> <regex> <new value>)
set (defines DEF1 DEF2 OTHER)
list (REPLACE defines "(.+[0-1]+)$" "NEW_\\1")
# result: NEW_DEF1 NEW_DEF2 OTHER

• TOUPPER, TOUPPER_AT, TOUPPER_ITEM, TOLOWER, TOLOWER_AT, TOLOWER_ITEM: change case of all list's elements.

# list (TOUPPER <list>)
# list (TOUPPER_AT <list> <index> [<index> ...])
# list (TOUPPER_ITEM <list> <value> [<value> ...])
# list (TOLOWER <list>)
# list (TOLOWER_AT <list> <index> [<index> ...])
# list (TOLOWER_ITEM <list> <value> [<value> ...])