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Comment by torginus | Hacker News Reader

I'm sorry but after reading your comment I can't seem to be able to decide if you favor writing the dynamic programming version or pulling in the constraint solver.

Both are correct in the sense that they give the right output, and I don't think pulling in a huge library (maintained by who knows and for how long) is going to be beneficial for maintenace. And having a good understanding of both the precise requirements, and the algorithms used to solve them also helps maintenance.

It's just having two dozen lines tucked of code away in a function in the repo seems infinitely more maintainable to me then using some giant framework (of possibly unknown quality) to solve the issue.

This is a general argument I'm making, not just applying to this constraint solver/

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There are other aspects to maintenance, like requirements change. In this case it's trivial to change or add new constraints to a constraint solver, whereas even small changes to a typical DP problem can require a total rethink of the approach. Extending the analogy to other kinds of dependencies left as an exercise for the reader.

Point being that software has many dimensions. Reducing the use of dependencies to fear of learning or thinking is a bit reductive in my opinion, even for stuff that seems simple initially.

Imo, deepending on the desired quality of the result and the amount and complexity of bespoke requirements, the more of the former are present, the more strongly I consider rolling something bespoke.

With out-of-the-box libraries, the more custom requirements I have, the more trouble I tend to have supporting them, and trying to make something do a thing it wasn't designed for, can erase initial gains very quickly. At least this has been my experience over the years.

I mean, it really depends. I'm writing models for some energy traders at the moment, and things were simple enough in the mvp that we could hand-roll our optimisations. But when we started having to map real contracts it got out of hand super fast. Linear constraints solvers have been a godsend, it makes adding new types of contacts and constraints really easy (and supports almost arbitrary kinds of optimisations).

It's just never as easy as "don't do this" or "always do this". But yeah, I agree with your gist, right tools for the right job and all that. Most of the time you don't know all requirements up front and it can make sense to hedge your bets in the interest of speed until you do.

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