.SETITEM index array value

Change the indexth element of array to be value. This similar to SETITEM, except that it does not check for circularity.

WARNING: Primitives whose names start with a period are dangerous. Their use by non-experts is not recommended. The use of .SETITEM can lead to circular list structures, which will get some primitives into infinite loops; unexpected changes to other data structures that share storage with the list being modified; crashes and core dumps if the BUTFIRST of a list is not itself a list; and the permanent loss of memory if a circular structure is released.

MAKE "myarray (ARRAY 3 0)
.SETITEM 2 :myarray 1
.SETITEM 1 :myarray 2
.SETITEM 0 :myarray 3
SHOW :myarray
{3 2 1}