[ajuc]

Technically you can implement map as reduce ;)

But yes - for me

    (defn factorial [n]
      (reduce * (range 1 (inc n))))

is slightly more readable than

    def factorial(n):
        result = 1
        for i in range(2,n+1):
           result *= i
        return result

I mean in this case the name kinda makes it obvious anyway :)

If the operation is conceptually accumulating something over the whole collection and if it's idiomatic in the language I'm using - I will use reduce. Same with map-y and filter-y operations.

But if I have to do some mental gymnastics to make the operation fit reduce - for loop it is. Or generator expression in case of python.