code-slides.nix

let
  #helpers
  file = stepNum: { filename, extension, focus?"" }:  ''
### ${filename}.${extension}
```${extension} ${focus}
${builtins.readFile ./step-${stepNum}/${filename}.${extension}}
```
  '';
in
''
<!--s-->
${file "1" {filename = "flake"; extension = "nix"; /*focus = "[|3-6,14|5-7]"; */}}
note:
- Flakes are the notice board and it gives a heads up what is in the project
- Flake allows us to use nix and its packages with a lock file 
- Flake allows you to describe an entire Git repository as a reliable collection of packages:
  - dev environments that contains dependecies related to your project 
      this is usually a good starting point when you try to "discover" a project 
  - fully nixified packages of the reporostiry
<!--v-->
${file "2" {filename = "flake"; extension = "nix"; }}
note:
- lets pick the nodejs eco system to start with 
<!--v-->
${file "2" {filename = "bash"; extension = "sh"; }}
note:
- here we run nix develop
- here we are assuming that the user that uses
our repo will know this commands exists
- and there are more then one command
- it will be nice to have them documented, or even better have them has one 
known command to serve as entry point
<!--v-->
${file "3" {filename = "server"; extension = "js"; }}
<!--s-->
${let step = file "3"; in ''
${step {filename = "flake"; extension = "nix"; }}
note:
- lets try to solve this by adding a nix default package to our flake
- this is a package that creates a shell script exectuable
- inside that script it contains the commands that we were executing manually before
- it is a bit meta 
- it will run nix develop 
- which will search a flake file in the current folder or in one of the parent folders 
and will try to run in the default devShell defined in it the node start server command
- lets see how the actual shell script looks like
---
- we can even add the package into our dev shell...
- when adding any package to the buildInputs it could be our default or the nodejs package 
  nix will append the bin folder to the PATH of the dev shell

- there is still an issue here we have infused 2 commands in one: node server.js and nix develop...
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
note:
- nix build
- similar to nix develop it will search for the flake
- and will evualate and build the default package in it
- this process run in "closed" nix building enviorment 
- which allows fetching of source code,configuring, patching, building
- this build process must end by creating a folder or a file in nix store
- when done by default it will create for us a result symlink to this file or folder in the current folder
---
''}
<!--s-->
${let step = file "4"; in ''
${step {filename = "flake"; extension = "nix";}}
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
''}
<!--s-->
${let step = file "5"; in ''
${step {filename = "commands"; extension = "nix"; }}
<!--v-->
${step {filename = "flake"; extension = "nix"; }}
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
''}
<!--s-->
${let step = file "6"; in ''
${step {filename = "commands"; extension = "nix"; }}
<!--v-->
${step {filename = "flake"; extension = "nix"; }}
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
''}
<!--s-->
${let step = file "7"; in ''
${step {filename = "commands"; extension = "nix"; }}
<!--v-->
${step {filename = "flake"; extension = "nix"; }}
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
''}
<!--s-->
${let step = file "8"; in ''
${step {filename = "commands"; extension = "nix"; }}
<!--v-->
${step {filename = "bash"; extension = "sh"; }}
<!--v-->
${step {filename = "flake"; extension = "nix"; }}
''}
''