#lang tabloid: Clickbait programming in Racket

This is a quick-and-dirty Racket implementation of Linus Lee’s Tabloid programming language (hereafter “OG Tabloid”), using the basic techniques taught in Beautiful Racket. Tabloid is a simple language so it’s perfect for practing and demonstrating Racket’s language-oriented programming (LOP) features.

The website and the README were the only things I consulted. This implementation can run the Fibonacci and factorial example programs, and generally gives the same results for any given Tabloid code (see below), but has not been exhaustively tested.

Any contributions and comments are of course welcome.

Thanks to Linus for this great project!

Use

This package is not currently available on the package server. To be able to run #lang tabloid programs in your Racket installation, clone this repo and run raco pkg install from within the project’s main folder.

Under the hood

The code is pretty well commented, so crack open main.rkt to start a guided tour.

Every #lang tabloid program evaluates to #<void>, which is the return value of PLEASE LIKE AND SUBSCRIBE

Differences from OG Tabloid

I made a token effort to get most programs to produce the same results here as in OG Tabloid. For example, performing math operations (PLUS, TIMES etc) on values that differ in type produces the same results in both implementations.

However, there are some differences. Most of these could be considered improvements, but they mostly result from conveniences afforded by Racket rather than from any special effort on my part.

Operator precedence: OG Tabloid’s parser doesn’t know about operator precedence, and in fact requires parentheses in order to use more than one infix operator in an experession. Racket Tabloid does allow these expressions to be chained without parentheses, and will correctly prioritize TIMES, DIVIDED BY and MODULO over PLUS and MINUS.

As an illustration, the program below produces a parsing error in OG Tabloid, and outputs 12! in this implementation:

#lang tabloid

YOU WON'T WANT TO MISS 7 PLUS 2 TIMES 3 MINUS 1

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Producing Output: In OG Tabloid, expressions that evaluate to a value (e.g. expressions like 10 or 1 IS ACTUALLY 2 appearing all by themselves) do not by themselves produce any output. In Racket Tabloid, such expressions do produce output on the REPL.

Shocking developments optional: Racket Tabloid allows you to return a value from a function without using SHOCKING DEVELOPMENT; the value of the last evaluated expression becomes the result of the function call.

Returning from any block: Racket Tabloid allows SHOCKING DEVELOPMENT to be used within any RUMOR HAS IT…END OF STORY block expression. The program below produces no output in OG Tabloid, and A! in Racket Tabloid:

#lang tabloid

EXPERTS CLAIM x TO BE 
  RUMOR HAS IT 
   WHAT IF (2 MODULO 2) IS ACTUALLY 0
    SHOCKING DEVELOPMENT 'A'
   LIES!
    'B'
  END OF STORY

YOU WON'T WANT TO MISS x

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