For implementation and code generation specification, check Implementation.

1. *Installing a CPython distribution.

   If you're already a user of CPython, you can skip this step.

   Otherwise, go to this official download page, download and install any valid distribution(>=3.5).

2. Installing the Python package purescripto, which will provide you the command pspy.

   Possible commands for installing can be:

   # if `pip` is in PATH
   pip install -U purescripto
   # if `python` is in PATH
   python -m pip install -U purescripto
   # if `pip3` is the correct command to install pkgs to Python3
   pip3 install -U purescripto

3. *Installing pspy-blueprint

   If purescripto didn't provide your an executable pspy-blueprint, you should manually install it from this repository:

   • Install from GitHub release page.
   • Install from source(Need Haskell stack): clone this repo, and use command stack install ., which will install pspy-blueprint to your .local PATH.

4. Installing nodejs, which is distributed with a command npm, and use npm to install purescript and its package manager spago:

   npm install -g purescript
   npm install -g spago

   You might check PureScript: Getting Started for more details.

5. git clone https://github.com/purescript-python/purescript-python-ffi-index ~/.pspy/mirrors/default.

   If you're using windows, remember to expand the user directory "~" to "C:\Users\twshe<username>".

6. Create an empty folder called hello-world somewhere appropriate,get in, and call

   spago init  # init purescript project
   pspy --init # init purescript-python local configuration
   

7. Add a key backend with value "pspy", to file spago.dhall of your hello-world project. This is an example:

    {-
    Welcome to a Spago project!
    You can edit this file as you like.
    -}
    { name = "my-project"
    , dependencies = [ "console", "effect", "psci-support" ]
    , packages = ./packages.dhall
    , sources = [ "src/**/*.purs", "test/**/*.purs" ]
    , backend = "pspy" -- !!NOTE THIS!!
    }

8. Write your code in src/**.purs, and use spago run to execute your project(the default entry module is Main).

PureScript is close to Haskell, hence a Haskell user can pick it up in few seconds.

The home of PureScript is PureScript.org, where you can find things involving documentations.

A major motivation for my working on PureScript is its lightweighted but awesome IDE support.

For VSCode users, installing the plugin PureScript IDE and File -> Preferences -> Settings -> (search purescript) -> Turn on "Add Spago sources" will be sufficient. No need to install some GitHub repo and build for 4 hours! And this IDE feels swift!

For each project, if your project directory tree is

- src
    - Main.purs
    - Mod
        - A.purs

If you have foreign definitions in module Mod.A, you need to create a directory python-ffi juxtaposing src, and it'll finally look like:

- python-ffi
   - Mod
      - A.py
- src
    - Main.purs
    - Mod
        - A.purs

It's now under GNU LESSER GENERAL PUBLIC LICENSE.

There're some reasons for why I have to choose this:

To make releases more user-friendly, the purescript-python compiler is now distributing in the form of static-linked binaries, which could run perfectly in each Linux distribution.

However, to achieve this, a Linux binary distribution have to statically link to some essential Haskell dependencies like integer-GMP and glibc, which're under LGPL.

Hence, we cannot avoid LGPL trivially as the development of alternative libraries(integer-simple or musl/uClibc) are either suspended or WIP. So we change LICENSE to LGPL.

Fortunately, purescript-python is just a compiler, which actually means you don't need to statically link to it.

Similar cases are other LGPL compilers/transpilers, like gcc/pandoc. We know they didn't trouble us in terms of their licenses, so purescript-python would not as well.