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0 pointsdhosek5y ago0 comments

I guess it depends on where you're doing the interviewing. I've had surprisingly unintelligent people get to me in the interviewing stages. It amazes me how many developers, experienced even, who can't write a simple recursive function. And we're not even looking at, "can you come up with a recursive function as a solution to this problem?" we're looking at "write a recursive function to calculate the factorial" as the question.

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joefourier5y ago

How often do recursive functions come up in your daily programming life? For me they're rare enough that it makes sense that many otherwise competent developers draw a blank when asked to write one in the context of a high-stress interview.

They may look clever, but they're often not the ideal solution compared to a simpler to understand, and often easier to optimise iterative solution. I write plenty of DSP, GPGPU programming, and computer vision, and I can't honestly remember the last time I wrote a recursive function.

sukilot5y ago

Recursive functions come up quite often when investigating the root cause of outages.

Unclear if that means we need candidates who are better at recursion, or better at avoiding recursion.

dhosekOP5y ago

Recursion is pretty fundamental in functional programming—it's preferred over loops. A smart compiler will do tail-call optimization and eliminate the overhead of increasing the stack size. Even if you're working in a non-FP development environment, knowledge of FP techniques makes one a stronger programmer. And recursion is not some esoteric technique in any event.

throwaway_pdp095y ago

> I write plenty of DSP, GPGPU programming, and computer vision ... I can't honestly remember the last time I wrote a recursive function.

Not remotely surprising is it. Hopefully if you went for a suitable job they wouldn't ask unsuitable questions. Then again, writing a recursive factorial should pain no-one.

dhosekOP5y ago

Exactly. I wasn't asking people to do something difficult. I don't think that there's a simpler recursive function than this, if you can't do this, then you don't have basic knowledge of what a recursive function is. I learned how to do this in high school.

lmilcin5y ago

It is not about how often they come up but whether you can think in an abstract way on a convoluted problem.

Think about IQ test which shows some abstract puzzles that have no connection with the real world. They are part of the test because they provide measurement points on tasks that require different types of abstract thinking without prerequisite knowledge.

Again, it is not possible to verify you have all the necessary knowledge for the job, nor would it be useful (no candidate knows everything for the position and if he did he would likely be overqualified).

I of course ask questions that test candidate's knowledge in the most useful areas, but at least part of the interview I want to devote to finding out how smart he/she is on abstract tasks that don't require some special knowledge.

sukilot5y ago

I don't want to let abstract convoluted problem solvers anywhere near my production systems

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dekhn5y ago

They come up about once a year for me. That's about how often I have to write a tree traversal.

sukilot5y ago

Why traverse a tree recursively and risk blowing your stack?

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joefourier5y ago

sukilot5y ago

Recursive functions come up quite often when investigating the root cause of outages.

Unclear if that means we need candidates who are better at recursion, or better at avoiding recursion.

dhosekOP5y ago

throwaway_pdp095y ago

> I write plenty of DSP, GPGPU programming, and computer vision ... I can't honestly remember the last time I wrote a recursive function.

Not remotely surprising is it. Hopefully if you went for a suitable job they wouldn't ask unsuitable questions. Then again, writing a recursive factorial should pain no-one.

dhosekOP5y ago

lmilcin5y ago

It is not about how often they come up but whether you can think in an abstract way on a convoluted problem.

sukilot5y ago

I don't want to let abstract convoluted problem solvers anywhere near my production systems

1 more reply

dekhn5y ago

They come up about once a year for me. That's about how often I have to write a tree traversal.

sukilot5y ago

Why traverse a tree recursively and risk blowing your stack?

2 more replies

j / k navigate · click thread line to collapse