I’m a physicist used to using Fortran90 for number crunching and Python for plotting and glue code. I’m learning Julia because of its ease of use, promised efficiency, and excellent math support. That said, there’s some habits and methods I’ve learned from Fortran programming that I’m unsure how to …

No, you don’t need a main() function. It is quite common to write scripts that just call lots of functions written by you or others. The important thing is to ensure that the functions that you are calling do not reference any nonconstant global variables. Global variables, by definition, are not…

Thank you! That’s actually very handy. Could you explain why the example program has a main() function, whereas @PeterSimon 's answer says the main() function is unnecessary?

I usually put runtime configuration into a JSON file. Very easy to read and write.

Switching away from Fortran is very worthwhile. Example: Replacing legacy code with Julia - Julia Community 🟣

main() is just a convenient wrapper. You can just as easily do f(g(h(x))) because functions are first class objects that can be fed to other functions.

I believe Leandro wanted to keep the structure of the two codes as similar a possible. One advantage of using the main function in Julia is that it keeps all the little (local) variables from polluting the global namespace, and from any possible unforeseen “action-at-a-distance” type bugs that migh…

[image] technocrat: You can just as easily do f(g(h(x))) because functions are first class objects that can be fed to other functions. Just a side note, that’s not an example of first-class functions, since no function there is being fed a function as it’s argument (unless g or h happen to re…

I was just trying to help OP with my own interrogation about best way of reading a parameter file, so I asked to a well known « expert » (I will not cite its name, see last part of this post) In Julia, reading a configuration file vs a parameter (input) file, recommended packages? I got a rather …

[image] jdad: I am quite surprised to be flagged « spammy/AI », as there is no code in my post, rather a factual analysis. I agree I did not perform myself the analysis, but I give the question and the source of the answer to be reproducible. Is that forbidden by community rules? How to convey i…

Not a direct answer to your questions, but I think it’s worth to mention the package DrWatson.jl It is very useful to manage simulations and the results. Other advantage, it imposes very little on the user and allows for different types of workflows.

One useful example of a struct that you will understand is Complex{T}. (Do I vaguely recall that Fortran has complex numbers natively? So does Julia in the sense that they’re in Base, but it still has to define their behavior somewhere . If you want a “non-native” example, neither has native support …

Structure and performance questions from a Fortran programmer: functions, global variables, array allocations, input files, and structs

New to Julia

stevengj June 3, 2026, 2:25pm 23

Yes, see the discourse guidelines:

Don’t post generative AI outputs (but direct human language translation and minor editing is ok).

See also the recent discussion here: Non-native English speakers and the use of language assistance

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Structure and performance questions from a Fortran programmer: functions, global variables, array allocations, input files, and structs

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