Using obviously synchronizable series expressions instead of loops

It has been known for a long time that series expressions (functional expressions on data aggregates) are easier to write and maintain than loops. However, as typically implemented, series expressions are much less efficient than loops. At the cost of placing modest limits on what can be written, obviously synchronizable series expressions solve this problem by guaranteeing that every series expression can be automatically converted into a highly efficient loop. It is demonstrated using Lisp and Pascal prototypes that obviously synchronizable series expressions can be added to any programming language