Arguments first and last are index values specifying the first and last elements of the range to replace. They are interpreted the same as index values for the command string index, supporting simple index arithmetic and indices relative to the end of the list. The index 0 refers to the first element of the list, and end refers to the last element of the list.
If either first or last is less than zero, it is considered to refer to the position before the first element of the list. This allows elements to be prepended.
If either first or last indicates a position greater than the index of the last element of the list, it is treated as if it is an index one greater than the last element. This allows elements to be appended.
If last is less than first, then any specified elements will be inserted into the list before the element specified by first with no elements being deleted.
The value arguments specify zero or more new elements to be added to the list in place of those that were deleted. Each value argument will become a separate element of the list. If no value arguments are specified, then the elements between first and last are simply deleted.
set lst {c d e f g}
→ c d e f g
ledit lst -1 -1 a b
→ a b c d e f g
Append to the list.
ledit lst end+1 end+1 h i
→ a b c d e f g h i
Delete third and fourth elements.
ledit lst 2 3
→ a b e f g h i
Replace two elements with three.
ledit lst 2 3 x y z
→ a b x y z g h i
set lst
→ a b x y z g h i