Always write a generalized version of your algorithm

Airspeed Velocity

Suppose you want to find the minimum value in an array. Well, the Swift standard library has you covered:

Ok that’s cool. But suppose you have an array of strings of integers and you want the minimum numeric value.

Well, I guess you could map them to Int and then use the same function:

Nope, compiler error. String.toInt returns an Int?, because maybe the string isn’t a number.

Fair enough. I happen to know with my intimate knowledge of the problem domain that we can just ignore non-numeric values. So maybe filter those out?

Nope, more compiler errors, because now we have only non-nil values, but they’re still optionals and an Int? doesn’t conform to Comparable. So maybe another map to force-unwrap the results (force unwrap is OK because the filter will guarantee no non-nil elements):¹

Ok that compiles now and does return the minimum numeric…

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