Imports and libraries

In the section we look at the way that imports and modules work in Charm.

Imports

Imports are introduced by the import headword.

A line in the import section can only have two forms: either simply a path to a library, expressed as a string:

import

"lib/strings.ch"

In this case the functions in the library will be in the strings namespace, e.g. strings.toUpperCase.

Alternatively, it can be a pair consisting of a preferred namespace and the path:

import

mathlib::"lib/math.ch" // Has namespace 'mathlib'.
NULL::"lib/fmt.ch"      // Has no separate namespace.

Use of NULL as a namespace means that the imported file isn't put into a separate namespace.

Imports as modules

An imported script can just be a static library. However, if it has a var section then the variables will be initialized; and if the script has an init command (as discussed later in the manual), it will be executed.

Namespaces can be chained: if your script imports foo which imports bar which has a function zort, then your script can call foo.bar.zort.

Standard libraries

Producing the standard libraries is a matter of wrapping Charm functions around Go functions, and so can be done easily and even automatically; and the developers at Google have already tested, optimized, and documented the library functions for us.

A world library for performing basic IO, file handling, and SQL interop, is imported into every script automatically.

Besides world, this version of Charm comes with six importable libraries: fmt, math, path, regexp, strings, and time, imported as in the examples above.

The following pages are in this section:

• The fmt library
• The math library
• The path library
• The regexp library
• The strings library
• The time library