Packages

Idris includes a simple build system for building packages and executables from a named package description file. These files can be used with the Idris compiler to manage the development process.

Package Descriptions

A package description includes the following:

  • A header, consisting of the keyword package followed by a package name. Package names can be any valid Idris identifier. The iPKG format also takes a quoted version that accepts any valid filename.
  • Fields describing package contents, <field> = <value>.

At least one field must be the modules field, where the value is a comma separated list of modules. For example, given an idris package maths that has modules Maths.idr, Maths.NumOps.idr, Maths.BinOps.idr, and Maths.HexOps.idr, the corresponding package file would be:

package maths

modules = Maths
        , Maths.NumOps
        , Maths.BinOps
        , Maths.HexOps

Other examples of package files can be found in the libs directory of the main Idris repository, and in third-party libraries.

Using Package files

Idris itself is aware about packages, and special commands are available to help with, for example, building packages, installing packages, and cleaning packages. For instance, given the maths package from earlier we can use Idris as follows:

  • idris2 --build maths.ipkg will build all modules in the package
  • idris2 --install maths.ipkg will install the package, making it accessible by other Idris libraries and programs.
  • idris2 --clean maths.ipkg will delete all intermediate code and executable files generated when building.

Once the maths package has been installed, the command line option --package maths makes it accessible (abbreviated to -p maths). For example:

idris2 -p maths Main.idr

Package Dependencies Using Atom

If you are using the Atom editor and have a dependency on another package, corresponding to for instance import Lightyear or import Pruviloj, you need to let Atom know that it should be loaded. The easiest way to accomplish that is with a .ipkg file. The general contents of an ipkg file will be described in the next section of the tutorial, but for now here is a simple recipe for this trivial case:

  • Create a folder myProject.
  • Add a file myProject.ipkg containing just a couple of lines:
package myProject

depends = pruviloj, lightyear
  • In Atom, use the File menu to Open Folder myProject.