7.3. Array Access Routines

Sather supports the standard array access syntax of square brackets. For instance:
a:ARRAY{INT} := |1,2,3|;
a[2] := 5;             -- Sets the third element of the array to 5
#OUT + a[0];           -- Prints out '1'
c:ARRAY2{INT} := ||1,2,3|,|4,5,6|,|7,8,9||;
#OUT + c[2,2];         -- Prints out '9'

However, the array bracket notation is not built into the array class. It is just a short hand for the routines aget and aset
a[2] := 5;   -- equivalent to a.aset(2,5);
#OUT + a[1]; -- equivalent to #OUT+a.aget(1);

Thus, classes which are not arrays can make use of the array notation as they please:
class INT is
   -- The standard integer class
   aget(i:INT):BOOL is -- returns the 'i'th bit of the integer

In order for a class to actually have an array portion, it must inherit from AREF{T} (if it is a reference class) or AVAL{T} if it is a value class. The array setting notation is not as useful for immutable classes, since any modification of an immutable class must return a whole new object.