julia training slides for 2022-06-08

opening early, there's still a tiny bit of TODOs

Guess this is valid as a 1st draft now

2022/2022-06-08_JuliaForNewcomers/slides/bootstrap.md

+<div class=leader>
+<i class="twa twa-axe"></i><i class="twa twa-carpentry-saw"></i><i class="twa twa-screwdriver"></i><i class="twa twa-wrench"></i><i class="twa twa-hammer"></i><br>
+Bootstrapping Julia
+</div>
+
+
+
+# Installing Julia
+
+Recommended method:
+
+- Download an archive from https://julialang.org/downloads/
+- Execute `julia` or `julia.exe` as-is
+- Link it to your `$PATH`
+
+Distribution packages usually work well too:
+
+- **Debians&Ubuntus**: `apt install julia`
+- **Iris/Aion**: `module add lang/Julia`
+
+
+
+# Life in REPL
+
+```julia
+user@pc $ julia
+
+julia> sqrt(1+1)
+1.4142135623730951
+
+julia> println("Well hello there!")
+Well hello there!
+
+julia> ?
+help?> sqrt
+
+sqrt(x)
+
+Computes the square root .....
+```
+
+
+
+# REPL modes
+
+Julia interprets some additional keys to make our life easier:
+
+- `?`: help mode
+- `;`: shell mode
+- `]`: packaging mode (looks like a box!)
+- `Backspace`: quits special mode
+- `Tab`: autocomplete anything
+- `\`... `Tab`: expand math characters
+
+
+
+
+# Managing packages from the package management environment
+
+-   Install a package
+
+```julia
+] add UnicodePlots
+```
+
+-   Uninstall a package
+
+```julia
+] remove UnicodePlots
+```
+
+
+
+# Loading libraries, modules and packages
+
+-   Load a local file (with shared functions etc.)
+
+```julia
+include("mylibrary.jl")
+```
+
+-   Load a package, add its exports to the global namespace
+
+```julia
+using UnicodePlots
+```
+
+
+
+# <i class="twa twa-light-bulb"> </i> How to write a standalone program?
+
+*Your scripts should communicate well with the environment!*
+(that means, among other, you)
+
+```julia
+#!/usr/bin/env julia
+
+function process_file(filename)
+
+  @info "Processing $filename..."
+
+  # ... do something ...
+
+  if error_detected
+    @error "something terrible has happened"
+    exit(1)
+  end
+end
+
+for file in ARGS
+    process_file(file)
+end
+```
+
+Correct processing of commandline arguments makes your scripts *repurposable*
+and *configurable*.
+
+
+
+
+# <i class="twa twa-light-bulb"></i> Workflow: Make a local environment for your script
+
+
+- Enter a local project with separate package versions
+
+```julia
+] activate path/to/project
+```
+
+- Install dependencies of the local project
+
+```julia
+] instantiate
+```
+
+- Execute a script with the project environment
+
+```sh
+$ julia --project=path/to/project script.jl
+```
+
+(Project data is stored in `Project.toml`, `Manifest.toml`.)