The sum of a list of numbers
When trying to explain the difference between functional programming languages and imperative languages, one of the examples people usually give is the sum of a list of numbers.
Someone will say, for example, that in Haskell the sum of a list of numbers can be calculated like this:
sum [1..10]
And the thesis is normally that this is much simpler and more elegant than doing a for loop, like so:
in sum = 0;
for(int x=1; x define a variable to keep my count and another variable for an iterator; now iterate over all the numbers from 1 to 10 and for each of them add it to the count variable. at the end of the loop, the result is in the count variable.
And that’s the difference between sum [1..10] and the sum(range(1,10)).