Here's some. I used to be extremely comfortable with Haskell, but things didn't go well when I tried using it for the first online programming contest I ever did. It was just too slow to write code in, compared to C++, which I hadn't used for years. Being able to plop down variables in front of a for loop, or print statements, or extra conditionals to handle some corner cases or break out of a loop, and to just casually mutate local variables, makes writing out a solution go a lot faster, with a lot less mental overhead from having to janitor variables between maps, folds, and whatnot.