Comment by chadash | Hacker News Reader

Comment by chadash | Hacker News Reader

> "I don’t see Julia a good replacement of Python. Julia has a long startup time. When you use a large package like Bio.jl, Julia may take 30 seconds to compile the code, longer than the actual running time of your scripts."

I think this is the crux of it. Python may not be the fastest language out there, but it's definitely one of the fastest languages to develop with, which is why it's such a hit with the academic research crowd.

Static typing and compilation are great features for many use cases, but if you are just prototyping something (and most academics are never going to write "production" code), it's nice to be able to try something, test it and then iterate and try again. When you have to compile, that iteration loop takes longer.

A few people here mentioned GoLang as a good alternative. Personally, I love the language, but it's really not very good for quick prototyping. As an example, the code won't compile with unused variables. This is great for production code but very impractical when you are testing some new algorithm.

I don't think this is entirely accurate. When you develop software, you don't repeatedly unload and load your dependencies (which is what causes Julia's startup time). You probably only develop one package, which you then reload one in a while. That causes very little lag in Julia. Similarly when working interactively, there you only suffer from startup time when you launch your session and use your heavy dependencies the first time.

Also, for what it's worth, I recreated his benchmarks in Julia and found a startup time of 5-6 seconds on my laptop. Not nothing, but compared to the time any FASTQ-processing operation usually takes, it's insignificant.

Julia' compile time latency does prevent you from e.g. calling a short Julia script in a loop, or from using Julia scripts that both have large dependencies and do very short-timed tasks. But I find that to be not very common in my workflow - especially since I usually don't use Julia as a small glue layer between C programs the way Python is often used.

A "prototype" software is sometimes a nice way to name some junk code. When I read that most academics are never going to write production code, they're prototyping, they need something to develop fast... it looks like most academics value fast writing more than correctness, which is not my experience.

As an anecdote, a friend of mine is an applied mathematician specializing in PDE and fluid dynamics. He used to code with C++, because that was what was used in the labs where he worked. Then he discovered Python and he thought it was so much easier, and still quite fast thanks to optimized libraries (written in C++ with a Python interface). But after a few months his enthusiasm had disappeared because of the runtime errors of his Python code. He didn't want to go back to full C++, though, and he still codes mostly with Python.

> "He didn't want to go back to full C++, though, and he still codes mostly with Python."

Exactly. It seems like he understands the tradeoffs and prefers quick iteration over "correctness".

In my experience, for computational "academic" code, the hard part is often coming up with the correct algorithm, not implementing that algorithm correctly. In software engineering, it's often the opposite.

You said it's not your experience, but then you give an anecdote which says where because fast writing was prioritized, he ended up with runtime errors...

Maybe the two-language problem is not a problem after all. I've been coming around to the idea of writing the core algorithms in a fast language with a lot of features around correctness, and the rest in whatever language is most productive. Learning another language isn't so bad as long as it's not an utter beast like C++.

Ideal if you can swing it. One of my professors used to prototype in Python for development speed and then re-implement in C++ for runtime speed. You get the best of both worlds in a sense.

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