coding-effectively

When designing features, think about properties upfront. This surfaces design gaps early.

| Does it have an inverse operation? | Roundtrip | decode(encode(x)) == x | | Is applying it twice the same as once? | Idempotence | f(f(x)) == f(x) | | What quantities are preserved? | Invariants | Length, sum, count unchanged | | Is order of arguments irrelevant? | Commutativity | f(a, b) == f(b, a) |

| Can operations be regrouped? | Associativity | f(f(a,b), c) == f(a, f(b,c)) | | Is there a neutral element? | Identity | f(x, 0) == x | | Is there a reference implementation? | Oracle | new(x) == old(x) | | Can output be easily verified? | Easy to verify | issorted(sort(x)) |