To split programs into meaningful units of components, Cloe provides a modules system. Modules are basically small parts of programs which are separated into files and imported by other modules.
There are 2 kinds of modules: main modules and submodules. Seen from a distance, programs in Cloe are trees consisting of main modules on top and subtrees of submodules under them.
- Main modules
Every module consists of multiple statements which are supposed to define variables or functions, or even import other modules.
Used in modules,
import statements make variables and functions belonging to other modules available there with their prefices.
(import "http") ; import a built-in module (import "./dir/some_module") ; import a local module (the actual filename is ./dir/some_module.cloe) ; Now you can use members of the imported modules. (let requests (http.getRequests ":8080")) (print (some_module.some_function 42))
Refer to variables.
Refer to functions.
Main modules are where side effects of programs are defined as top-level expressions in addition to the statements. Note that only one main module exists per program while a program can contain multiple submodules.
Expressions with side effects like printing text on terminal or sending HTTP responses must be defined at the top level of main modules and these are called top-level expressions when they must be guaranteed to be evaluated on execution of the programs.
(print "Hello, world!")
You can also expand lists of effects into top-level expressions.
..[(print "Good morning") (print "Good afternoon") (print "Good evening")]
Submodules are modules imported by other ones which can be both main modules or submodules. In contrast to main modules, top-level expressions cannot be used in submodules while the other statements can be as well.