A bare bones for loop is the implementation of replicateM. There are more complex combinators than replicateM, e.g: filterM, zipWithM, and more... Which you wou

A bare bones for loop is the implementation of replicateM. There are more complex combinators than replicateM, e.g: filterM, zipWithM, and more... Which you would need more than duplicating a bare bones loop at every occurence. The code I pasted above uses "do" notation to write a monadic parser. The parser parses the format started by a <date>:<time> and if those set a date larger than some point in the past, it parses the continuation of the text differently. Which part of the code are you having difficulty understanding?