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The USE statement

USE creates a local alias for a fully qualified namespace or namespaced function. Use it when repeating a long qualified name would make a script harder to read.

Aliases are resolved when the script is compiled. USE does not import, load, or register a module.

Alias a namespace

Use a namespace alias as the first segment of a qualified function name:

example.fql
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USE IO::NET::HTTP AS HTTP RETURN HTTP::GET("https://api.example.com/data")

Here, HTTP::GET(...) resolves to IO::NET::HTTP::GET(...).

The syntax is:

example.fql
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USE target AS alias

For a namespace alias, target is the fully qualified namespace and alias is the shorter name used by the rest of the script.

Alias a function

USE can also alias a specific namespaced function. The alias is then called without a namespace prefix:

example.fql
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USE IO::NET::HTTP::GET AS GET RETURN GET("https://api.example.com/data")

Here, GET(...) resolves to IO::NET::HTTP::GET(...).

Place USE before the script body

USE declarations belong in the script header. Put them before variable declarations, function declarations, function calls, and terminal statements such as RETURN or a top-level FOR.

A script may declare more than one alias:

example.fql
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USE IO::FS AS FS USE IO::NET::HTTP::GET AS GET LET data = FS::READ("/tmp/data.json") RETURN [data, GET("https://api.example.com/data")]

Resolution rules

  • Aliases and qualified function names are case-sensitive. HTTP, http, and Http are different names.
  • Reusing an alias for a different target produces a compile-time name error.
  • An alias does not make its target available. The runtime still needs to register the namespace or function named by the target.
  • Runtime capabilities may differ between the CLI, browser runtime, and embedding applications, so an alias can only call functions provided by the current environment.

Next steps

Learn Module Functions Call namespaced functions and create aliases with the USE statement. Learn Script structure How a Ferret script is organized, top to bottom. Runtime modules Modules Install, configure, register, and manage modules in an embedded runtime.