Changes the first member of
list to be
list input must be list and cannot be empty.
WARNING: Primitives whose names start with a period are dangerous. Their use by non-experts is not recommended. The use of .SETFIRST can lead to circular list structures, which causes infinite loops for some primitives; unexpected changes to other data structures that share storage with the list being modified; and the permanent loss of memory if a circular structure is released.
MAKE "mylist [1 2 3] .SETFIRST :mylist 0 SHOW :mylist[0 2 3]