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See aggregation functions defined inductively and implemented using recursion.

Learn how in many cases, tail-recursion and the accumulator trick can be used to avoid stack-overflow errors.

Watch as general aggregation is implemented and see duality theorems capturing the relationship between left folds and right folds.

Through the work of Sergei Winitzki and Richard Bird.

keywords: duality theorems, fold, folding, foldl, foldleft, foldr, foldright, functional programming, haskell, left fold, mathematical induction, recursion, recursive datatype, recursive function, richard bird, right fold, scala, sergei winitzki, structural induction, tail-recursion

August 11, 2020