Arrays

An array is a named, growable list of values. There is no declaration: writing to name[index] creates the array.

scores[0] = 10
scores[1] = 20
scores[2] = scores[0] + scores[1]
println(scores[2])     # 30

Indices and growth

• The index is any integer expression: scores[i + 1], scores[scores[0] - 9].
• Indices start at 0.
• Writing past the end grows the array; cells in between are filled with the integer 0.
• Elements are untyped: an array can hold integers, floats and strings together.

data[0] = 1.5
data[1] = 'two'
data[3] = 4        # data[2] becomes 0

Reading

Reading a missing array, an index past the end, or a negative index is a runtime error: Runtime error, then ARRREAD: index out of range (or array does not exist), and the program stops. Writing to a negative index fails the same way (ARRWRITE: negative index).

Notes

• Arrays and variables have separate namespaces: a = 7 and a[0] = 1 can coexist.
• Arrays are global and cannot be passed to or returned from routines, or assigned as a whole. Loop over the index instead.
• There is no built-in length. Keep the count in a variable.
• Array storage is managed by the garbage collector.
• A program can use at most 256 distinct array names.

Debugging

The debugger’s variables command lists every array with its name, length and contents, and the disassembler shows array names on ARRWRITE / ARRREAD.