FOR EACH Loops

FOR EACH iterates over array-like values and executes a block for every item.

When to use it

Use FOR EACH when you need side effects or multiple statements per item (such as building accumulators).

Syntax

FOR EACH item IN input.items {
    OUTPUT { name: item.name };
}

Filtering items

Add a WHERE clause to keep only matching elements.

FOR EACH item IN input.items WHERE item.qty > 1 {
    OUTPUT { name: item.name, qty: item.qty };
}

Mutating within a loop

Use SET to update accumulators as you iterate.

LET totals = { count: 0, sum: 0 };

FOR EACH item IN input.items WHERE item.qty > 0 {
    SET totals.count = totals.count + 1;
    SET totals.sum = totals.sum + item.qty;
}

OUTPUT totals;

Pitfalls

• FOR is a synonym of FOR EACH, but mixing both in one file can hurt readability.
• WHERE is optional; omit it if you do not need filtering.
• For single-expression transforms, prefer array comprehensions.

Try it

Load collection-transforms and compare loops to MAP/FILTER/REDUCE alternatives.

Related

• Array Comprehensions
• Statements