Category "fold"

Fold in Scade Suite is confusing me

So I know how the reduce, accumulator and how fold works in C++, Python, etc... But for some reason in Scade Suite it's kinda confusing to me. Scade Suite Examp

foldl function in SML/NJ: Right-hand-side of clause doesn't agree with function result type

I have a function named dfs which produces a list of all visited nodes in a graph represented by a list of tuples such as [(node1,node2,weight),....] and I get

Is implementing the words function possible without a postprocessing step after folding?

Real World Haskell, chapter 4, page 98 of the print asks if words can be implemented using folds, and this is my question too: Is it possible? If not, why? If i