You're being too enthusiastic/wrong: there is a cost to Result and Option even in the good case. There still has to be a branch to check if there actually was n

You're being too enthusiastic/wrong: there is a cost to Result and Option even in the good case. There still has to be a branch to check if there actually was no error. Result and Option are similar to error codes in C and have a similar cost/benefit trade-off, although of course with all the ADT/type-safety goodness.