kookie
/
nomicon
1
0
Fork 0
Code Issues Projects Releases 1 Activity

doc/python: update python version references

Browse Source
main
Martin Weinelt 2 years ago committed by Jonathan Ringer
parent f1ac3fa330
commit 4566beb390
No known key found for this signature in database
GPG Key ID: 5C841D3CFDFEC4E0
1 changed files with 35 additions and 32 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 67
      doc/languages-frameworks/python.section.md

67
doc/languages-frameworks/python.section.md
Unescape View File

@ -8,9 +8,9 @@
Several versions of the Python interpreter are available on Nix, as well as a
high amount of packages. The attribute `python3` refers to the default
interpreter, which is currently CPython 3.9. The attribute `python` refers to
interpreter, which is currently CPython 3.10. The attribute `python` refers to
CPython 2.7 for backwards-compatibility. It is also possible to refer to
specific versions, e.g. `python38` refers to CPython 3.8, and `pypy` refers to
specific versions, e.g. `python39` refers to CPython 3.9, and `pypy` refers to
the default PyPy interpreter.
Python is used a lot, and in different ways. This affects also how it is
@ -26,10 +26,10 @@ however, are in separate sets, with one set per interpreter version.
The interpreters have several common attributes. One of these attributes is
`pkgs`, which is a package set of Python libraries for this specific
interpreter. E.g., the `toolz` package corresponding to the default interpreter
is `python.pkgs.toolz`, and the CPython 3.8 version is `python38.pkgs.toolz`.
is `python.pkgs.toolz`, and the CPython 3.9 version is `python39.pkgs.toolz`.
The main package set contains aliases to these package sets, e.g.
`pythonPackages` refers to `python.pkgs` and `python38Packages` to
`python38.pkgs`.
`pythonPackages` refers to `python.pkgs` and `python39Packages` to
`python39.pkgs`.
#### Installing Python and packages {#installing-python-and-packages}
@ -54,7 +54,7 @@ with `python.buildEnv` or `python.withPackages` where the interpreter and other
executables are wrapped to be able to find each other and all of the modules.
In the following examples we will start by creating a simple, ad-hoc environment
with a nix-shell that has `numpy` and `toolz` in Python 3.8; then we will create
with a nix-shell that has `numpy` and `toolz` in Python 3.9; then we will create
a re-usable environment in a single-file Python script; then we will create a
full Python environment for development with this same environment.
@ -70,10 +70,10 @@ temporary shell session with a Python and a *precise* list of packages (plus
their runtime dependencies), with no other Python packages in the Python
interpreter's scope.
To create a Python 3.8 session with `numpy` and `toolz` available, run:
To create a Python 3.9 session with `numpy` and `toolz` available, run:
```sh
$ nix-shell -p 'python38.withPackages(ps: with ps; [ numpy toolz ])'
$ nix-shell -p 'python39.withPackages(ps: with ps; [ numpy toolz ])'
```
By default `nix-shell` will start a `bash` session with this interpreter in our
@ -81,8 +81,8 @@ By default `nix-shell` will start a `bash` session with this interpreter in our
```Python console
[nix-shell:~/src/nixpkgs]$ python3
Python 3.8.1 (default, Dec 18 2019, 19:06:26)
[GCC 9.2.0] on linux
Python 3.9.12 (main, Mar 23 2022, 21:36:19)
[GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy; import toolz
```
@ -102,13 +102,16 @@ will still get 1 wrapped Python interpreter. We can start the interpreter
directly like so:
```sh
$ nix-shell -p 'python38.withPackages(ps: with ps; [ numpy toolz requests ])' --run python3
these derivations will be built:
/nix/store/xbdsrqrsfa1yva5s7pzsra8k08gxlbz1-python3-3.8.1-env.drv
building '/nix/store/xbdsrqrsfa1yva5s7pzsra8k08gxlbz1-python3-3.8.1-env.drv'...
created 277 symlinks in user environment
Python 3.8.1 (default, Dec 18 2019, 19:06:26)
[GCC 9.2.0] on linux
$ nix-shell -p "python39.withPackages (ps: with ps; [ numpy toolz requests ])" --run python3
this derivation will be built:
/nix/store/mpn7k6bkjl41fm51342rafaqfsl10qs4-python3-3.9.12-env.drv
this path will be fetched (0.09 MiB download, 0.41 MiB unpacked):
/nix/store/5gaiacnzi096b6prc6aa1pwrhncmhc8b-python3.9-toolz-0.11.2
copying path '/nix/store/5gaiacnzi096b6prc6aa1pwrhncmhc8b-python3.9-toolz-0.11.2' from 'https://cache.nixos.org'...
building '/nix/store/mpn7k6bkjl41fm51342rafaqfsl10qs4-python3-3.9.12-env.drv'...
created 279 symlinks in user environment
Python 3.9.12 (main, Mar 23 2022, 21:36:19)
[GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
>>>
@ -147,7 +150,7 @@ Executing this script requires a `python3` that has `numpy`. Using what we learn
in the previous section, we could startup a shell and just run it like so:
```ShellSession
$ nix-shell -p 'python38.withPackages(ps: with ps; [ numpy ])' --run 'python3 foo.py'
$ nix-shell -p 'python39.withPackages(ps: with ps; [ numpy ])' --run 'python3 foo.py'
The dot product of [1 2] and [3 4] is: 11
```
@ -210,12 +213,12 @@ create a single script with Python dependencies, but in the course of normal
development we're usually working in an entire package repository.
As explained in the Nix manual, `nix-shell` can also load an expression from a
`.nix` file. Say we want to have Python 3.8, `numpy` and `toolz`, like before,
`.nix` file. Say we want to have Python 3.9, `numpy` and `toolz`, like before,
in an environment. We can add a `shell.nix` file describing our dependencies:
```nix
with import <nixpkgs> {};
(python38.withPackages (ps: [ps.numpy ps.toolz])).env
(python39.withPackages (ps: [ps.numpy ps.toolz])).env
```
And then at the command line, just typing `nix-shell` produces the same
@ -229,7 +232,7 @@ What's happening here?
imports the `<nixpkgs>` function, `{}` calls it and the `with` statement
brings all attributes of `nixpkgs` in the local scope. These attributes form
the main package set.
2. Then we create a Python 3.8 environment with the `withPackages` function, as before.
2. Then we create a Python 3.9 environment with the `withPackages` function, as before.
3. The `withPackages` function expects us to provide a function as an argument
that takes the set of all Python packages and returns a list of packages to
include in the environment. Here, we select the packages `numpy` and `toolz`
@ -240,7 +243,7 @@ To combine this with `mkShell` you can:
```nix
with import <nixpkgs> {};
let
pythonEnv = python38.withPackages (ps: [
pythonEnv = python39.withPackages (ps: [
ps.numpy
ps.toolz
]);
@ -378,8 +381,8 @@ information. The output of the function is a derivation.
An expression for `toolz` can be found in the Nixpkgs repository. As explained
in the introduction of this Python section, a derivation of `toolz` is available
for each interpreter version, e.g. `python38.pkgs.toolz` refers to the `toolz`
derivation corresponding to the CPython 3.8 interpreter.
for each interpreter version, e.g. `python39.pkgs.toolz` refers to the `toolz`
derivation corresponding to the CPython 3.9 interpreter.
The above example works when you're directly working on
`pkgs/top-level/python-packages.nix` in the Nixpkgs repository. Often though,
@ -392,11 +395,11 @@ and adds it along with a `numpy` package to a Python environment.
with import <nixpkgs> {};
( let
my_toolz = python38.pkgs.buildPythonPackage rec {
my_toolz = python39.pkgs.buildPythonPackage rec {
pname = "toolz";
version = "0.10.0";
src = python38.pkgs.fetchPypi {
src = python39.pkgs.fetchPypi {
inherit pname version;
sha256 = "08fdd5ef7c96480ad11c12d472de21acd32359996f69a5259299b540feba4560";
};
@ -414,7 +417,7 @@ with import <nixpkgs> {};
```
Executing `nix-shell` will result in an environment in which you can use
Python 3.8 and the `toolz` package. As you can see we had to explicitly mention
Python 3.9 and the `toolz` package. As you can see we had to explicitly mention
for which Python version we want to build a package.
So, what did we do here? Well, we took the Nix expression that we used earlier
@ -742,7 +745,7 @@ If we create a `shell.nix` file which calls `buildPythonPackage`, and if `src`
is a local source, and if the local source has a `setup.py`, then development
mode is activated.
In the following example we create a simple environment that has a Python 3.8
In the following example we create a simple environment that has a Python 3.9
version of our package in it, as well as its dependencies and other packages we
like to have in the environment, all specified with `propagatedBuildInputs`.
Indeed, we can just add any package we like to have in our environment to
@ -750,7 +753,7 @@ Indeed, we can just add any package we like to have in our environment to
```nix
with import <nixpkgs> {};
with python38Packages;
with python39Packages;
buildPythonPackage rec {
name = "mypackage";
@ -828,9 +831,9 @@ and in this case the `python38` interpreter is automatically used.
### Interpreters {#interpreters}
Versions 2.7, 3.7, 3.8 and 3.9 of the CPython interpreter are available as
respectively `python27`, `python37`, `python38` and `python39`. The
aliases `python2` and `python3` correspond to respectively `python27` and
Versions 2.7, 3.7, 3.8, 3.9 and 3.10 of the CPython interpreter are available
as respectively `python27`, `python37`, `python38`, `python39` and `python310`.
The aliases `python2` and `python3` correspond to respectively `python27` and
`python39`. The attribute `python` maps to `python2`. The PyPy interpreters
compatible with Python 2.7 and 3 are available as `pypy27` and `pypy3`, with
aliases `pypy2` mapping to `pypy27` and `pypy` mapping to `pypy2`. The Nix

Write Preview
Loading…
Cancel
Save