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doc: update python manual to reference python 3.8 instead of 3.5

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Improvement suggested in #87094
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Benjamin Hipple 2020-05-09 12:58:00 -04:00
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72
doc/languages-frameworks/python.section.md
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@ -9,7 +9,7 @@
Several versions of the Python interpreter are available on Nix, as well as a
high amount of packages. The attribute `python` refers to the default
interpreter, which is currently CPython 2.7. It is also possible to refer to
specific versions, e.g. `python35` refers to CPython 3.5, and `pypy` refers to
specific versions, e.g. `python38` refers to CPython 3.8, and `pypy` refers to
the default PyPy interpreter.
Python is used a lot, and in different ways. This affects also how it is
@ -25,10 +25,10 @@ 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 3.5 version is `python35.pkgs.toolz`.
is `python.pkgs.toolz`, and the CPython 3.8 version is `python38.pkgs.toolz`.
The main package set contains aliases to these package sets, e.g.
`pythonPackages` refers to `python.pkgs` and `python35Packages` to
`python35.pkgs`.
`pythonPackages` refers to `python.pkgs` and `python38Packages` to
`python38.pkgs`.
#### Installing Python and packages
@ -50,7 +50,7 @@ to create an environment with `python.buildEnv` or `python.withPackages` where
the interpreter and other executables are able to find each other and all of the
modules.
In the following examples we create an environment with Python 3.5, `numpy` and
In the following examples we create an environment with Python 3.8, `numpy` and
`toolz`. As you may imagine, there is one limitation here, and that's that
you can install only one environment at a time. You will notice the complaints
about collisions when you try to install a second environment.
@ -61,7 +61,7 @@ Create a file, e.g. `build.nix`, with the following expression
```nix
with import <nixpkgs> {};
python35.withPackages (ps: with ps; [ numpy toolz ])
python38.withPackages (ps: with ps; [ numpy toolz ])
```
and install it in your profile with
```shell
@ -79,7 +79,7 @@ Nixpkgs set, e.g. using `config.nix`,
{ # ...
packageOverrides = pkgs: with pkgs; {
myEnv = python35.withPackages (ps: with ps; [ numpy toolz ]);
myEnv = python38.withPackages (ps: with ps; [ numpy toolz ]);
};
}
```
@ -101,7 +101,7 @@ environment system-wide.
{ # ...
environment.systemPackages = with pkgs; [
(python35.withPackages(ps: with ps; [ numpy toolz ]))
(python38.withPackages(ps: with ps; [ numpy toolz ]))
];
}
```
@ -118,7 +118,7 @@ recommended method is to create an environment with `python.buildEnv` or
`python.withPackages` and load that. E.g.
```sh
$ nix-shell -p 'python35.withPackages(ps: with ps; [ numpy toolz ])'
$ nix-shell -p 'python38.withPackages(ps: with ps; [ numpy toolz ])'
```
opens a shell from which you can launch the interpreter
@ -131,7 +131,7 @@ The other method, which is not recommended, does not create an environment and
requires you to list the packages directly,
```sh
$ nix-shell -p python35.pkgs.numpy python35.pkgs.toolz
$ nix-shell -p python38.pkgs.numpy python38.pkgs.toolz
```
Again, it is possible to launch the interpreter from the shell. The Python
@ -140,14 +140,14 @@ that specific interpreter.
##### Load environment from `.nix` expression
As explained in the Nix manual, `nix-shell` can also load an
expression from a `.nix` file. Say we want to have Python 3.5, `numpy`
expression from a `.nix` file. Say we want to have Python 3.8, `numpy`
and `toolz`, like before, in an environment. Consider a `shell.nix` file
with
```nix
with import <nixpkgs> {};
(python35.withPackages (ps: [ps.numpy ps.toolz])).env
(python38.withPackages (ps: [ps.numpy ps.toolz])).env
```
Executing `nix-shell` gives you again a Nix shell from which you can run Python.
@ -158,7 +158,7 @@ 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 3.5 environment with the `withPackages` function.
2. Then we create a Python 3.8 environment with the `withPackages` function.
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`
@ -170,7 +170,7 @@ To combine this with `mkShell` you can:
with import <nixpkgs> {};
let
pythonEnv = python35.withPackages (ps: [
pythonEnv = python38.withPackages (ps: [
ps.numpy
ps.toolz
]);
@ -188,13 +188,13 @@ option, with which you can execute a command in the `nix-shell`. We can
e.g. directly open a Python shell
```sh
$ nix-shell -p python35Packages.numpy python35Packages.toolz --run "python3"
$ nix-shell -p python38Packages.numpy python38Packages.toolz --run "python3"
```
or run a script
```sh
$ nix-shell -p python35Packages.numpy python35Packages.toolz --run "python3 myscript.py"
$ nix-shell -p python38Packages.numpy python38Packages.toolz --run "python3 myscript.py"
```
##### `nix-shell` as shebang
@ -231,11 +231,11 @@ building Python libraries is `buildPythonPackage`. Let's see how we can build th
buildPythonPackage rec {
pname = "toolz";
version = "0.7.4";
version = "0.10.0";
src = fetchPypi {
inherit pname version;
sha256 = "43c2c9e5e7a16b6c88ba3088a9bfc82f7db8e13378be7c78d6c14a5f8ed05afd";
sha256 = "08fdd5ef7c96480ad11c12d472de21acd32359996f69a5259299b540feba4560";
};
doCheck = false;
@ -260,8 +260,8 @@ 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. `python35.pkgs.toolz` refers to the `toolz`
derivation corresponding to the CPython 3.5 interpreter.
for each interpreter version, e.g. `python38.pkgs.toolz` refers to the `toolz`
derivation corresponding to the CPython 3.8 interpreter.
The above example works when you're directly working on
`pkgs/top-level/python-packages.nix` in the Nixpkgs repository. Often though,
you will want to test a Nix expression outside of the Nixpkgs tree.
@ -273,13 +273,13 @@ and adds it along with a `numpy` package to a Python environment.
with import <nixpkgs> {};
( let
my_toolz = python35.pkgs.buildPythonPackage rec {
my_toolz = python38.pkgs.buildPythonPackage rec {
pname = "toolz";
version = "0.7.4";
version = "0.10.0";
src = python35.pkgs.fetchPypi {
src = python38.pkgs.fetchPypi {
inherit pname version;
sha256 = "43c2c9e5e7a16b6c88ba3088a9bfc82f7db8e13378be7c78d6c14a5f8ed05afd";
sha256 = "08fdd5ef7c96480ad11c12d472de21acd32359996f69a5259299b540feba4560";
};
doCheck = false;
@ -290,12 +290,12 @@ with import <nixpkgs> {};
};
};
in python35.withPackages (ps: [ps.numpy my_toolz])
in python38.withPackages (ps: [ps.numpy my_toolz])
).env
```
Executing `nix-shell` will result in an environment in which you can use
Python 3.5 and the `toolz` package. As you can see we had to explicitly mention
Python 3.8 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
@ -435,7 +435,7 @@ 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 3.5
In the following example we create a simple environment that has a Python 3.8
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
@ -443,7 +443,7 @@ Indeed, we can just add any package we like to have in our environment to
```nix
with import <nixpkgs> {};
with python35Packages;
with python38Packages;
buildPythonPackage rec {
name = "mypackage";
@ -505,9 +505,9 @@ with import <nixpkgs> {};
( let
toolz = callPackage /path/to/toolz/release.nix {
buildPythonPackage = python35Packages.buildPythonPackage;
buildPythonPackage = python38Packages.buildPythonPackage;
};
in python35.withPackages (ps: [ ps.numpy toolz ])
in python38.withPackages (ps: [ ps.numpy toolz ])
).env
```
@ -515,8 +515,8 @@ Important to remember is that the Python version for which the package is made
depends on the `python` derivation that is passed to `buildPythonPackage`. Nix
tries to automatically pass arguments when possible, which is why generally you
don't explicitly define which `python` derivation should be used. In the above
example we use `buildPythonPackage` that is part of the set `python35Packages`,
and in this case the `python35` interpreter is automatically used.
example we use `buildPythonPackage` that is part of the set `python38Packages`,
and in this case the `python38` interpreter is automatically used.
## Reference
@ -662,7 +662,7 @@ following are specific to `buildPythonPackage`:
variables which will be available when the binary is run. For example,
`makeWrapperArgs = ["--set FOO BAR" "--set BAZ QUX"]`.
* `namePrefix`: Prepends text to `${name}` parameter. In case of libraries, this
defaults to `"python3.5-"` for Python 3.5, etc., and in case of applications
defaults to `"python3.8-"` for Python 3.8, etc., and in case of applications
to `""`.
* `pythonPath ? []`: List of packages to be added into `$PYTHONPATH`. Packages
in `pythonPath` are not propagated (contrary to `propagatedBuildInputs`).
@ -960,7 +960,7 @@ has security implications and is relevant for those using Python in a
When the environment variable `DETERMINISTIC_BUILD` is set, all bytecode will
have timestamp 1. The `buildPythonPackage` function sets `DETERMINISTIC_BUILD=1`
and [PYTHONHASHSEED=0](https://docs.python.org/3.5/using/cmdline.html#envvar-PYTHONHASHSEED).
and [PYTHONHASHSEED=0](https://docs.python.org/3.8/using/cmdline.html#envvar-PYTHONHASHSEED).
Both are also exported in `nix-shell`.
@ -1014,7 +1014,7 @@ with import <nixpkgs> {};
packageOverrides = self: super: {
pandas = super.pandas.overridePythonAttrs(old: {name="foo";});
};
in pkgs.python35.override {inherit packageOverrides;};
in pkgs.python38.override {inherit packageOverrides;};
in python.withPackages(ps: [ps.pandas])).env
```
@ -1036,7 +1036,7 @@ with import <nixpkgs> {};
packageOverrides = self: super: {
scipy = super.scipy_0_17;
};
in (pkgs.python35.override {inherit packageOverrides;}).withPackages (ps: [ps.blaze])
in (pkgs.python38.override {inherit packageOverrides;}).withPackages (ps: [ps.blaze])
).env
```