Problem Statement
What is the difference between reduce and fold operations?
Explanation
The fold function takes an initial accumulator value and a lambda that combines the accumulator with each element, like numbers dot fold open paren 0 close paren open curly acc comma num arrow acc plus num close curly. The reduce function doesn't take an initial value but uses the first element as the initial accumulator.
Fold is safer for empty collections as it returns the initial value, while reduce throws an exception on empty collections. Use reduceOrNull for null-safe reduction on potentially empty collections.
Both are useful for aggregating collection elements into a single value like sums, products, or building strings, with fold being more flexible due to the explicit initial value allowing different result types than the element type.
Practice Sets
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