Lurch core classes

Tutorial: Lurch Node REPL

Lurch Node REPL

$\newcommand{\lode}{\mathbb{LODE}}$This tutorial covers how to run an instance of the node REPL in a terminal which has all of the LDE commands and supporting utilities preloaded. This is useful for debugging and experimenting with the functions and classes defined in the repository. This initialized version of node can be thought of as Lurch node, or simply $\lode$ for short.

The other tutorials cover what kinds of objects you can create in Lode and what you can do with them.

Running $\lode$

To run $\lode$ from the command line in a terminal at the the root folder of your local copy of this source code repository simply type the command npm run lode. Alternatively, you can run it from the scripts subfolder of the root folder with the command node lode. (If you have not yet set up a copy of this repository with the appropriate Node.js version installed, see our GitHub README, which explains how to do so.)

> node lode

Welcome to 𝕃𝕠𝕕𝕖 - the Lurch Node app
(type .help for help)
▶︎

You are now at the Lurch Node REPL command prompt. All of the exported modules in the src/index.js file in this repository. For example, you can now do things like this (see LogicConcept and toPutdown):

Welcome to 𝕃𝕠𝕕𝕖 - the Lurch Node app
(type .help for help)
▶︎ LogicConcept.fromPutdown(`{ :Hello ( World ! ) }`)[0].toPutdown()
'{ :Hello (World !) }'
▶︎

Since creating and viewing LogicConcepts in putdown notation is often what we want, $\lode$ provides a shortcut for constructing LCs and displays LCs in Putdown notation by default.

▶︎ LogicConcept.fromPutdown(`{ :Hello ( World ! ) }`)[0].toPutdown()
'{ :Hello (World !) }'
▶︎ lc(`{ :Hello ( World ! ) }`)  // constructs the same thing
{ :Hello (World !) }

There is a similar feature for MathConcepts using smackdown.

$\lode$ also loads Algebrite. So you can do numerical and algebraic calculations such as these (see the Algebrite documentation for details).

▶︎ Algebrite.run(`2^100`)
'1267650600228229401496703205376'
▶︎ Algebrite.run(`(x+1)^10`)
'x^10+10*x^9+45*x^8+120*x^7+210*x^6+252*x^5+210*x^4+120*x^3+45*x^2+10*x+1'

$\lode$ also defines compute as a synonym for Algebrite.run, and print as a synonym for console.log.

▶︎ compute(`2^100`)
'1267650600228229401496703205376'
▶︎ print(compute(`(x+1)^10`))
x^10+10*x^9+45*x^8+120*x^7+210*x^6+252*x^5+210*x^4+120*x^3+45*x^2+10*x+1

If you want to inspect the Object structure of an LC (or any object) instead of seeing its Putdown rendering, you can use the command inspect.

▶︎ X = lc(`A`)
A
▶︎ inspect(X)
Symbol {
  _dirty: true,
  _parent: null,
  _children: [],
  _attributes: Map(1) { 'symbol text' => 'A' },
  _origin: null,
  _feedbackEnabled: true,
  _feedbackQueue: []
}

You can type .features in $\lode$ to see the current list of features.