SCREAMSCRIPT

The language of your screams

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SCREAMSCRIPT is a dynamic programming language heavily influenced by the Lox programming language. One might even say I took my implementation from the Tree-Walk Interpreter component of Crafting Interpreters, then just edited the source so that keywords, identifiers, etc. could only be CAPTIAL SCREAM CASED, because that's exactly what I did. I even left the class names in place.

Why

Because I wanted to take a joke at work a little too far.

Interesting Tidbits

In the process of "making" SCREAMSCRIPT there were some interesting items of note that popped up:

Variable vs Class Identifiers

This implementation of Lox/SCREAMSCRIPT doesn't distinguish identifiers as class or variable types. It's a big ol' Map that stores everything together. As a result, the casing-convention of CapitalCasing class names and using lowercase for variable names was really the only thing keeping them from colliding. Without further changes, it's possible to define a class and override it accidentally (or purposefully, it's a dynamic programming language where this is technically designed to be as such, even in Lox).

$ ./runScreamRepl.sh 
     
BUILD SUCCESSFUL in 1s
4 actionable tasks: 4 executed

AHHHHHHH > CLASS BAGEL {}
AHHHHHHH > PRINT BAGEL;
BAGEL
AHHHHHHH > VAR B = BAGEL();
AHHHHHHH > PRINT B;
BAGEL INSTANCE
AHHHHHHH > VAR BAGEL = B;
AHHHHHHH > PRINT BAGEL;
BAGEL INSTANCE
AHHHHHHH > VAR C = BAGEL();
CAN ONLY CALL FUNCTIONS AND CLASSES!
[LINE 1]
AHHHHHHH > PRINT "OHHHHHHHHH";
OHHHHHHHHH

Keywords

Keywords should be SCREAM'ed. Like everything else. That's how you know it's all important. This really only required a few small changes in the Scanner and TokenType classes. There were however a few cases where Java String literals were used instead of a static variable, which also hand replaced.

String Variables

The contents of Strings need to SCREAM. The Scanner was updated accordingly to signal to the user they've done wrong by not screaming. If you don't scream it, you don't believe it.

Why don't people normalize text in SCREAM rather that lowercase? The world may never know.

Error Messages

Error messages were also manually converted to SCREAM. I did at a .toUpperCase call to the method that creates the error, but this gave a small appreciation for the places we need error handling throughout the language impl.

Running

I feel like there shouldn't need to be a disclaimer that SCREAMSCRIPT is not a production language. But if you are inclined to run this, here's how you'd do it.

REPL

runScreamRepl.sh is a very, very simple shell script in the root of this project that runs the build step (for the language) and starts the REPL:

$ ./runScreamRepl.sh 

BUILD SUCCESSFUL in 1s
4 actionable tasks: 4 executed
AHHHHHHH > VAR I = "HELLO WORLD!";
AHHHHHHH > PRINT I;
HELLO WORLD!
AHHHHHHH >

Scream Files

runScreamFile.sh is a very, very simple shell script in the root of this project that runs the build step (for the language) and runs a provided file. Examples live in scr/main/resources/scream-scripts, and still use the .scream extension.

For bacon.scream:

CLASS BACON {
    EAT() {
        PRINT "CRUNCH CRUNCH CRUNCH!";
    }
}

BACON().EAT();

We can run it as follows:

$ ./runScreamFile.sh -- src/main/resources/scream-scripts/ch12-classes/bacon.scream 

BUILD SUCCESSFUL in 1s
4 actionable tasks: 4 executed
CRUNCH CRUNCH CRUNCH!