Version: Next

#import

The #import directive is specific to the LIGO compiler. It provides the support for a minimal module/namespace system.

For more information about namespaces, see Namespaces.

Namespaces get more handy when they can be made from a file, separate from our own program, like a library: when we import a namespace from such a file, we automatically obtain a namespace encapsulating all the definitions in it. This will become very handy for organising large contracts, as we can divide it into different files, and the namespace system keeps the naming space clean (no need for name mangling).

Generally, we will take a set of definitions that can be naturally grouped by functionality, and put them together in a separate file. For example, we can create a file euro.jsligo:

export type t = nat;

export const add = (a: t, b: t): t => a + b;

export const one: t = 1n;
export const two: t = 2n;

In another file, we can import euro.jsligo as a namespace, and use its definitions. For example, we can create a main.jsligo that imports all definitions from euro.jsligo as the namespace Euro:

#import "gitlab-pages/docs/preprocessor/src/import/euro.jsligo" "Euro"

type storage = Euro.t;

const tip = (s : storage) : storage =>
  Euro.add (s, Euro.one);

Importing namespaces

When you import a file with the #import directive, LIGO packages the file as a namespace. Therefore, any namespaces in the file are sub-namespaces of that namespace.

However, the namespace does not export those sub-namespaces automatically. As a result, if you import a file that contains namespaces, those namespaces are not accessible.

To work around this limitation, add the @public decorator to the namespaces in the file. For example, this file defines the Euro type as a namespace with the @public decorator:

// This file is gitlab-pages/docs/preprocessor/src/import/euro_namespace_public.jsligo

@public
namespace Euro {
  export type t = nat;
  export const add = (a: t, b: t) : t => a + b;
  export const one: t = 1n;
  export const two: t = 2n;
};

Because the namespace is public, you can access it as a sub-namespace when you import the file into another file:

#import "gitlab-pages/docs/preprocessor/src/import/euro_namespace_public.jsligo" "Euro_import"

type euro_balance = Euro_import.Euro.t;

const add_tip = (s: euro_balance): euro_balance =>
  Euro_import.Euro.add(s, Euro_import.Euro.one);

Importing namespaces​

Importing namespaces