funcity

A functional language interpreter with text processing, easy embeddable!

What is this?

This is a lightweight functional language processor implemented in TypeScript, featuring syntax extensions for text processing. It includes a CLI application and a library package containing only the core engine.

funcity can be considered a type of text template processor. For example, entering code like this:

Today is {{if weather.sunny}}nice{{else}}bad{{end}} weather.

Evaluates the value of the weather variable manually bound to the core engine beforehand and generates different text outputs:

Today is bad weather.

The if ... else ... end statements in the text indicate that the script is being executed. So, you might ask, what makes this a "Functional language"? Or how is it different from existing text processors?

Let me show you another equivalent example:

Today is {{cond weather.sunny 'nice' 'bad'}} weather.

This is an example of function application, inserting the result of applying three arguments to the cond function. The first argument is a conditional expression.

The following code may further interest you:

{{
set printWeather (fun w (cond w.sunny 'nice' 'bad'))
}}
Today is {{printWeather weather}} weather.

• fun defines an anonymous lambda function.
• set performs a mutable binding in the current scope.

Furthermore, you can easily integrate this interpreter into your application:

// Input script
const script = "Today is {{cond weather.sunny ‘nice’ 'bad'}} weather.";

// Run the interpreter
const variables = buildCandidateVariables();
const logs: FunCityLogEntry[] = [];
const text = await runScriptOnceToText(script, variables, logs);

// Display the result text
console.log(text);

In other words, Funcity is a processing system that brings the power of functional programming to text template processors, enabling seamless integration into applications!

Features

• A lightweight functional language processor for handling untyped lambda calculus. Adopted the simplest possible syntax. Additionally, selected the syntax extensions that should be prioritized for text processing.
• All function objects are treated as asynchronous functions. You do not need to be aware that they are asynchronous functions when applying them.
• There is also a CLI using the core engine. The CLI has both REPL mode and text processing mode.
• The core engine includes a tokenizer, parser, and reducer (interpreter).
• The core engine library is highly independent, requiring no dependencies on other libraries or packages. It can be easily integrated into your application.
• Parsers and interpreters support both interpreting pure expressions and interpreting full text-processing syntax. This means that even when an interpreter for a purely functional language is required, it is possible to completely ignore the (somewhat incongruous) syntax of text processing.
• Allows pre-binding of useful standard function implementations.

Installation (CLI)

TODO:

npm install -D funcity-cli

Or, global installation:

npm install -g funcity-cli

Installation (Library)

npm install funcity

Documentation

For detailed documentation and advanced features, please visit our GitHub repository.

Note

funcity was separated from the document site generator mark-the-ripper during its design phase, as it seemed better suited to function as an independent scripting engine.

Therefore, mark-the-ripper can leverage the power of funcity's functional language.

License

Under MIT.