Basically you want to always use the least powerful tool you can to solve a problem. When applicable, map is better than foldl not because it's more concise, bu

Basically you want to always use the least powerful tool you can to solve a problem. When applicable, map is better than foldl not because it's more concise, but because it tells the reader that the result is a list of the same length of the input, and the elements of the input are processed independently. Similarly, foldl is better than raw recursion because it tells the reader that every element in the input list is being processed in order, rather than potentially anything happening. There's nothing wrong with using the more powerful tools when you need them (such as when implementing the more restricted tools). It's just that needing them frequently is a sign that you're doing weird things and should take a second look at your design to make sure there isn't a better way to do things.