`Mix.install(:decimal)` should also work out of the box IMO.
On Thu, 21 Jan 2021 03:18:44 -0800 (PST)
"woj...@wojtekmach.pl" <woj...@wojtekmach.pl> wrote:
> A minor addition: I'd like to add a shortcut so you can write
> `Mix.install([:decimal])` instead of `Mix.install([{:decimal, ">=
> 0.0.0"}])`.
>
> > The only downside of this approach compared to global dependencies
> > is
> that each IEx session is a blank session - but that can be
> streamlined in the future.
>
> Agreed. I didn't mention this in the proposal but here's a trick I've
> been using:
>
> # ~/.iex.exs
> unless Code.ensure_loaded?(Mix) do
> Mix.install([
> :decimal,
> :jason,
> :nimble_csv,
> {:requests, github: "wojtekmach/requests"}
> ])
> end
>
> This means however that when you start a session, you won't be able
> to call `Mix.install` again. In those cases I'd `iex --dot-iex ""` to
> ignore my global config.
>
>
> czwartek, 21 stycznia 2021 o 12:05:18 UTC+1 José Valim napisał(a):
>
> > I have discussed this with Wojtek and I am in favor of this
> > proposal.
> >
> > Elixir was designed to support scripting but I constantly hear that
> > the lack of some quality of life features, such as trapping exits,
> > limited IO handling, lack of support for dependencies, etc make it
> > so even advanced Elixir developers don't end-up using Elixir for
> > regular single-file scripts.
> >
> > I have never been a fan of global dependencies. Between global
> > dependencies (not easily reproducible and with implicit
> > dependencies) and Mix projects (fully reproducible with explicit
> > dependencies), this sounds like a reasonable compromise (explicit
> > dependencies reproducible within requirements). The only downside
> > of this approach compared to global dependencies is that each IEx
> > session is a blank session - but that can be streamlined in the
> > future.
> >
> > Note the goal here is not to replace escripts either. Escripts have
> > the full-backing of a project, with dependencies, multiple source
> > files and tests. If it is anything beyond experimentation or more
> > than a couple dozen lines, then you do want a complete project.
> >
> > TL;DR: +1
> >
> > On Thu, Jan 21, 2021 at 11:40 AM woj...@wojtekmach.pl <
> > woj...@wojtekmach.pl> wrote:
> >
> >> Today, the only way to use dependencies in Elixir is by first
> >> adding them to the current Mix project or installing them as
> >> archives. This makes Elixir less than ideal for simple tasks where
> >> you'd usually use a scripting language, e.g. download a JSON file,
> >> parse it, extract some data. This is also adding pressure for a
> >> more "batteries-included" approach in the stdlib to make these
> >> simple tasks more convenient to accomplish and require neither
> >> creating a Mix project nor installing dependencies.
> >>
> >> I'd like to propose adding a `Mix.install` function that will
> >> download, compile, and load given dependencies into the VM.
> >>
> >> Here's how we could use it from an IEx session:
> >>
> >> $ iex
> >> iex> Decimal.new(42)
> >> ** (UndefinedFunctionError) function Decimal.new/1 is
> >> undefined (module Decimal is not available)
> >> Decimal.new(42)
> >> iex> Mix.install([{:decimal, "~> 2.0"}])
> >> :ok
> >> iex> Decimal.new(42)
> >> #Decimal<42>
> >>
> >> Or from a script:
> >>
> >> $ cat run.exs
> >> Mix.install([
> >> {:decimal, "~> 2.0"},
> >> {:jason, "~> 1.0"}
> >> ])
> >> IO.puts Jason.encode!(Decimal.new(42))
> >>
> >> $ elixir run.exs
> >> "42"
> >>
> >> You need to call `Mix.install` in your VM and explicitly list all
> >> your dependencies. And if you start a new VM, you'd have to call
> >> `Mix.install` again.
> >>
> >> Under the hood, the `Mix.install` starts Mix and creates a
> >> temporary Mix project to install and load the dependencies and
> >> unloads the temporary project when it's done. For simplicity, the
> >> initial implementation allows you to only call this function
> >> outside of a Mix project and you can only call it once in a given
> >> VM.
> >>
> >> The temporary project is preserved across runs so if you start
> >> another VM and call `Mix.install` with the same set of
> >> dependencies, they'll be loaded right away without needing to
> >> download or compile them. Each set of dependencies will have it's
> >> own temporary directory, roughly:
> >> `/tmp/mix_installs/<md5_of_deps>`.
> >>
> >> The location and the layout of the temporary project is considered
> >> an implementation detail that users shouldn't depend on.
> >>
> >> The fact that the resulting `mix.lock` file is hidden from the
> >> users presents challenges around reproducibility and updating
> >> deps. If you pin your deps to specific versions, a call to
> >> `Mix.install` will give consistent results, however if you use
> >> version requirements like `~> 1.0`, it may give different results
> >> depending on what the deps resolve to at at given time. Similarly,
> >> if there's a new version of a package that satisfies a given
> >> version requirement, `Mix.install` won't automatically install it
> >> as it already cached the dependency. For this, you'll be able to
> >> pass a `force: true` flag to bypass the cache and install &
> >> compile from scratch for a given set of dependencies. This will
> >> also help if your install somehow got into an inconsistent state.
> >>
> >> ### Reproducibility
> >>
> >> Another way of quickly installing and using dependencies is via
> >> workspaces, you'd install and automatically load dependencies
> >> within a given workspace. That brings questions about
> >> reproducibility.
> >>
> >> Imagine you write a piece of Elixir code that uses dependencies
> >> and share it with people, how reproducible is it?
> >>
> >> - using Mix project, the dependencies are fully reproducible given
> >> the Mix project maintains a `mix.lock` file
> >>
> >> - using `Mix.install`, the dependencies are reproducible within
> >> the specified version requirements
> >>
> >> - using global state like workspaces, the dependencies are not
> >> reproducible. If you ask a user to run your script, you need to
> >> tell them what dependencies they need to install
> >>
> >> Between global dependencies having very weak reproducibility and
> >> Mix projects being fully reproducible, `Mix.install` is a
> >> compromise where you can reasonably reproduce things within a list
> >> of requirements.
> >>
> >> ### Further reading
> >>
> >> Thanks to https://hex.pm/packages/teex authors for exploring some
> >> of these ideas!
> >>
> >> Also see https://github.com/wojtekmach/playground for an earlier
> >> proof-of-concept and
> >> https://github.com/elixir-lang/elixir/compare/master...wojtekmach:wm-mix-install
> >>
> >> for a work-in-progress implementation.
> >>
> >> --
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> >> .
> >>
> >
>
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