sle

The sle (Simple Language Experiments) is a Node.js package that supports the building of applications offering the following features:

• Using the mrequire function it provides the ability to refer to packages that are stored in a github repository. This has the benefit of not needing an external file to indicate what are the exact version numbers of dependent packages.
• Allows intrinsic tests, called assumptions, to be include in source files thereby reducing the need to export the internal implementation of a package in order to support extrinsic unit testing.

mrequire

Dependencies to external packages is achieved by introducing the function

  mrequire

which takes a single string parameter describing the package that is to be included. The format of this parameter is

  handler:package:version

• handler

  Within sle there are support for two different handlers: core and github. The core handler will refer to a package that is stored in

  https://github.com/sle-js

  whilst the github handler will refer to the package that is referenced by the entire package component.

• package

  The name of the package that the handler will reference.

• version

  The labelled name which is used as a version indicator for the required package.

Core Example

Given the following piece of code:

  const Array = mrequire("core:Native.Data.Array:1.0.0");

This will download the following project out of github located at

https://github.com/sle-js/lib-Native.Data.Array

This source code will be placed into the directory

~/.sle/core/Native.Data.Array/1.0.0

off of the user's home directory. Note that only the code against the label 1.0.0 will be placed into this directory.

Finally the file index.js is then returned as a require to the caller.

Github Example

Given the following piece of code:

  const Array = mrequire("github:graeme-lockley/mn-Native.Data.Array:1.0.0");

This will download the following project out of github located at

https://github.com/graeme-lockley/mn-Native.Data.Array

This source code will be placed into the directory

~/.sle/github/graeme-lockley/mn-Native.Data.Array/1.0.0

off of the user's home directory. Note that only the code against the label 1.0.0 will be placed into this directory.

Finally the file index.js is then returned as a require to the caller.

Assumptions

Any function that is defined within a source file can have any number of assumptions to be included in the file. These assumptions are then executed when the source file is loaded and, in the event of an assumption failing, will cause the loading of the source file to be aborted.

The following are illustrative examples of using assumption and assumptionEqual:

//- Get the number of elements within an array.
//= length :: Array a -> Int
const length = a =>
    a.length;
assumption(length([]) === 0);
assumption(length([1, 2, 3]) === 3);


//= indexOf :: String -> String -> Maybe Int
const indexOf = pattern => s => {
    const index = s.indexOf(pattern);

    return index === -1
        ? Maybe.Nothing
        : Maybe.Just(index);
};
assumptionEqual(indexOf("world")("hello"), Maybe.Nothing);
assumptionEqual(indexOf("hello")("hello"), Maybe.Just(0));
assumptionEqual(indexOf("ll")("hello"), Maybe.Just(2));