[saulpw]

Some people like Peter Norvig prefer top-down, hackers like me and you prefer bottom-up. Many problems can be solved either way. But for some problems, if you use the wrong approach, you're gonna have a bad time. See Ron Jeffries' attempt to solve sudoku.

The top-down (mathematical) approach can also fail, in cases where there's not an existing math solution, or when a perfectly spherical cow isn't an adequate representation of reality. See Minix vs Linux, or OSI vs TCP/IP.

[lxe]

Fair point about problem-fit - some problems do naturally lend themselves to one approach over the other.

But I think the Sudoku example is less about top-down vs bottom-up and more about dogmatic adherence to abstractions (OOP in that case). Jeffries wasn't just using a 'hacker' approach - he was forcing everything through an OOP lens that fundamentally didn't fit the problem structure.

But yes, same issue can happen with the 'mathematical' approach - forcing "elegant" closed-form thinking onto problems that are inherently messy or iterative.

[senderista]

I don’t think his failure had anything to do with OOP. He failed because he deliberately refused to think systematically about the problem before writing code, per the dictates of TDD.

[kenjackson]

I'd argue that everyone solves problems bottoms up. It's just that some people have done the problem before (or a variant of it) so they have already constructed a top-down schema for it.

[js8]

No, there's a difference. The difference is whether you work in constraint space (top down) or in solution space (bottom up). Top down is effectively adding constraints until there is a single solution.

[liquid_bluing]

The hacker’s mentality is like that of the painter who spends months on a portrait in order to produce a beautiful but imperfect likeness, marked with his own personal style, which few can replicate and people pay a lot for. The mathematical approach is to take a photo because someone figured out how to perfectly reproduce images on paper over a hundred years ago and I just want a picture, dammit, but the camera’s manual is in Lojban.

IMO, the mathematical approach is essentially always better for software; nearly every problem that the industry didn’t inflict upon itself was solved by some egghead last century. But there is a kind of joy in creating pointless difficulties at enormous cost in order to experience the satisfaction of overcoming them without recourse to others, I suppose.