---
tags: seminar series
---

# Package development in Julia

:::danger
**General info**
- **Video connection details:**
- Zoom ID: 643 1441 2511
- Zoom password: rse
- Zoom invite link: https://uit.zoom.us/j/64314412511?pwd=K2VNTEw5VWVUSjMydVpqd3lieWVhUT09
- **Contact:**
- **Date and time**: Wednesday 18th August 2021 13:00 CEST
- **This page:** https://hackmd.io/@nordic-rse/package-development-julia
- **Setup instructions:** https://github.com/lucaferranti/juliaPackageDevelopment/
:::

## Icebreaker

* What have you used Julia for in the past?
* everything from numerical methods to web development :D
* Nothing! Here to learn more about it.
* nothing yet, only few experiments while going through small tutorials +1
* nothing yet, but looking forward to learning about it :)
* Played around with lattice theories in Julia (Ising model and similar)
* Haven't done anything yet! But hoping to learn soon :)
* ...
* ...
* ...

* What makes you interested in Julia?
* The cool promo t-shirt
* Typed language with the potential for fast code
* Solving the "two-language problem" - combining flexiblity/modularity with performance. +1
* I have heard that Julia has many geospatial libraries that make geoprocessing faster than with python:thinking_face:
* https://juliageo.org/
* :heart_eyes:
* use emojis as variable names :smile_cat:
* Is this possible!?
* Yes, I can demo it soon
* :100: :fire:
* ...
* ...
* ...

## About the series

This is the first event in the Nordic RSE seminar series.
* Reminder about starting recording
* Find out about future events:
* Check https://nordic-rse.org/events/seminar-series/.
* Follow [@nordic_rse](https://twitter.com/nordic_rse) on Twitter for announcements
* Join the [Nordic RSE stream](https://coderefinery.zulipchat.com/#narrow/stream/213720-nordic-rse) of the CodeRefinery chat
* Suggest speakers:
* on the [Nordic RSE stream](https://coderefinery.zulipchat.com/#narrow/stream/213720-nordic-rse)
* by creating an issue on the [Nordic RSE website repository](https://github.com/nordic-rse/nordic-rse.github.io/issues)

## About the Nordic RSE

* Represents Research Software Engineers in the Nordics.
* Check out [nordic-rse.org/](https://nordic-rse.org/) for other activities.
* Registering as an association this fall.
* To become a member, fill in the [membership form](https://forms.gle/qCVVRGXPi3Hq7inW6).

## Speaker

Today's speaker is Luca Ferranti,
* a computer science PhD student at the University of Vaasa
* the developer of [IntervalLinearAlgebra.jl](https://github.com/JuliaIntervals/IntervalLinearAlgebra.jl)
* and [juliaintervals.github.io](https://juliaintervals.github.io/)

## Setup instructions

See setup instructions: https://github.com/lucaferranti/juliaPackageDevelopment/

## Agenda
- Julia REPL+environments
- Creating packages from scratch
- structure of a typical Julia package
- package development workflow
- Tools for creating and managing documentation
- Tools for testing
- Contributing to existing packages

## Ask your questions here

* It checks compatibility by looking at semantic versioning?
- short answer: yes

* Can you please summarize again what the difference was between Project.toml and Manifest.toml?
- Project.toml: more general information, but no info about their versions
- Project.toml listst packages you have installed manually in the environment
- so Manifest.toml is like a "lock" file in other languages?
- Yes, it is similar
- Manifest.toml contains all information to replicate your environment exactly.

* Why are there the semicolons inside the Template() and GitHubActions()?
- In Julia, name parameters are separated by a ;
- for example, ```function f(x, y; z=1)``` to define function `f` with one z optional parameter.

* How do you get back to julia> after being in package mode?
* press backspace (delete the invisible ] or ;)

* Sorry I missed it: How did you create the mycoolpackage?
* thanks :)

* Can you use `@edit` on function defined inside REPL instead of source file?
* No, it needs to be in a source file.

* Would it be bad practice or technically not possible to define tests in the same place where code is defined? To avoid changing two files every time you want to move something around.
* The test package looks for `test/runtests.jl` (at least by default, I don't know if you can change it)
* but you can `@include` files in other paths in the `test/runtests.jl` file.
* It is good practice to have tests in the `test` folder. You might also want to add some tests to `src/subpackage/tests`, for example.

* ...
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