−A fold packages that skeleton into one function, taking an initial value, or seed, and a combining function, or step. The initial value is the result before any element has been seen and the input to the first step; the combining function uses the result so far and the next element to produce a new result. That intermediate result is the accumulator. In C#, LINQ Aggregate performs this job.
+A fold packages that traversal into one function that takes an initial value, or seed, and a combining function, or step: the seed is both the result before any element has been seen and the input to the first step, while the combining function uses the result so far and the next element to produce a new result. That intermediate result is the accumulator, and LINQ Aggregate performs this job in C#.
