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85 lines
3.2 KiB
Markdown
85 lines
3.2 KiB
Markdown
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Welcome to Idris2!
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==================
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<style>
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body {
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width: 80%;
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max-width: 700px;
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margin: auto;
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}
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code {
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background-color: whitesmoke;
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}
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pre code {
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display: block;
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}
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</style>
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[Idris](https://www.idris-lang.org/) is a programming language designed to encourage
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_Type-Driven Development_.
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### Getting started
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Once you have [installed Idris2](https://idris2.readthedocs.io/en/latest/tutorial/starting.html#getting-started)
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you can write a simple hello-world by opening a `Main.idr` file and writing:
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```idris
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module Main
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||| My first Idris2 function
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main : IO ()
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main = putStrLn "Hello, and welcome to Idris2!"
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```
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You can run this example by using the `--exec ENTRYPOINT` option.
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The command `idris2 --exec main Main.idr` will compile the module and immediately run `main`.
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The line starting with a triple pipe (`|||`) attaches documentation to the identifier. You
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can consult it by loading the file in the REPL (`idris2 Main.idr`) and querying the compiler
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using the `:doc` command: `:doc main` will return:
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Main.main : IO ()
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My first Idris2 function
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Visibility: private
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You should be able to use `:doc` on identifiers (e.g. `main`, `IO`, `()`, `putStrLn`, etc.) and
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keywords (`module`, `:`, `=`, `private`, etc.) and hopefully get helpful information.
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### Libraries shipped with the compiler
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Here are links to the automatically generated documentation for the libraries shipped with the
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**bleeding edge** version of the compiler. The documentation for the latest **released** version
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is available on the [idris-lang.org](https://www.idris-lang.org/pages/documentation.html) site.
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#### [Prelude](https://idris-lang.github.io/Idris2/prelude)
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The `prelude` is always implicitly loaded unless you use the `--no-prelude` command-line option.
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This is where the built-in types are bound, where the core data types (`List`, `Nat`, `Equal`, etc.)
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and interfaces (`Eq`, `Show`, `Functor`, etc.) are defined.
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#### [Base](https://idris-lang.github.io/Idris2/base)
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`base` contains all the basics needed to write small programs. Its modules can be used by adding
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an `import` statement to the top of your file.
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In [`Data.List`](https://idris-lang.github.io/Idris2/base/docs/Data.List.html) for instance you
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will find functions to `take` or `drop` values from a list, or `partition` it using a given predicate.
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You can explore the content of a namespace like `Data.List` by using `:browse Data.List` in the REPL.
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For more information about specific entries, you can then use `:doc`.
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#### [Contrib](https://idris-lang.github.io/Idris2/contrib)
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The `contrib` library contains a bit of everything. It will eventually be disbanded in favour of
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third-party packages once we have a convenient package manager. To use modules defined in it, you
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can pass the `-p contrib` option to `idris2`.
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#### [Linear](https://idris-lang.github.io/Idris2/linear)
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`linear` is the add-on to `base` you'll need for programs using linearity. Similarly to `contrib`,
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you will need to pass `-p linear` to `idris2` to use modules defined in it.
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#### [Papers](https://idris-lang.github.io/Idris2/papers)
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`papers` is not installed by default.
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It contains complex examples that are lifted from academic papers using dependent typeds
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and demonstrates advanced language features.
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