Bags

A Bag is a collection of Values. A Value can appear more than once; its multiplicity is how many times it appears.

Build a Bag

Write Values of one kind between braces, separated by commas or new lines:

{1, 2, 2} // {1, 2'2}

{
  "red"
  "blue"
  "blue"
} // {"blue"'2, "red"}

A Bag has no order: the REPL lists its Values sorted. 'n repeats each occurrence n times:

"apple"'3 // {"apple"'3}

{1, 2}'2 // {1'2, 2'2}

% keeps one occurrence of each Value:

{1, 1, 2}% // {1, 2}

Empty Bags

SakaQL has no null: missing data is an empty Bag. An empty Bag names the kind of Values it could hold, here num, the numbers:

num:{} // num:{}

Sets explains names such as num.

Combine Bags

These operators combine two Bags of the same kind:

Operation	Example	Result
Union: add the counts	{1, 1} | {1, 2}	{1'3, 2}
Distinct union: keep one of each	{1, 1} |% {1, 2}	{1, 2}
Difference: subtract the counts, down to zero	{1'3, 2} \+ {1, 2'2}	{1'2}
Distinct difference	{1'3, 2} \% {1, 2'2}	{1}
Product: multiply the counts of shared Values	{1'2, 2} & {1'3, 3}	{1'6}
Distinct product	{1'2, 2} &% {1'3, 3}	{1}
Fallback: the right Bag when the left one is empty	num:{} ?? {7, 8}	{7, 8}

{1, 1} | {1, 2} // {1'3, 2}