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A slightly-modified brainfuck that compiles to JVM bytecode

What is brainfrick?

Brainfrick is an extension of Brainfuck, an esoteric programming language based on only 8 different instructions; two to move a pointer, one each to increment or decrement the value at the pointer, two that allow for control flow, and one each for pulling input and pushing output. Brainfrick’s extensions allow it to be be compiled for and run on the JVM; it extends brainfuck’s simple syntax with a minimal set of instructions and syntax necessary for interacting with classes.


Maven Central Gradle Plugin Portal

Brainfrick provides a gradle plugin for compiling brainfrick code, and the runtime libraries are available on maven central. To use, apply the plugin and add the runtime libraries as a dependency:

plugins {
    id 'io.github.lukebemish.brainfrick' version '<plugin-version>'

repositories {

dependencies {
    implementation 'io.github.lukebemish.brainfrick:brainfrick-runtime:<version>'

Brainfrick code can be written in .frick files inside of the brainfrick folder within a source set: for instance, src/main/brainfrick/helloWorld.frick. Brainmaps are referenced from .frick files by relative path, and should have the .map extension.


To allow references to JVM classes and methods within a brainfuck-like environment, brainfrick requires the user to define any number of brainmaps. These are ordered lists of classes, methods, and field getters or setters. They take a form such as shown below:

// At index 0, we define a class
public class brainfrick.test.TestFunction implements java.util.function.Function
    // At index 1, we define a method on that class.
    public java.lang.Object apply(java.lang.Object)
    public new() -> java.lang.Object new()
// We can also reference classes we won't be defining
class java.lang.Object
abstract public class brainfrick.test.TestField
    get java.lang.Object storedObject
    static get java.lang.String staticString
    put java.lang.Object storedObject
    abstract java.lang.Object someMethod()

More details on brainmap syntax can be found at the brainmap specification. Brainmaps are referenced at the beginning of a brainfrick source file, and are integrated into classes at compile time. For instance, if the previous map was saved as, a corresponding brainfrick source file might be:

// Brainmaps to use are declared before anything else. Any number can be declared; they will
// be appended together at compile time.
// This syntax opens a class definition - in this case, the class at index 0
    // And this opens up a method definition
        // Your code implementing "apply" would go here
    // Methods and constructors are declared the same way
        // Static blocks can be defined like so. Returning early from one static block returns early from
        // all future ones as well.
// A "-" tells the compiler to skip this class or method - in this case, we don't want to redefine Object!
    // A ";" on its own for a method definition defines, but skips, an abstract method.

The code itself is an extended version of normal brainfuck syntax:

Command Description
> Moves the pointer one to the right. Pointer locations can be any integer value.
< Moves the pointer one to the left
+ Increments the pointed to location by one. Numbers will be increased by one, null will become 1, false will become true, and objects that implement Incrementable will be incremented.
- Decrements the pointed to location by one. Numbers will be decreased by one, null will become -1, true will become false, and objects that implement Decrementable will be decremented.
[ If the value at the pointer is zero-like (zero, false, null, or a Zeroable where isZero is true), jumps to after the matching ] instruction.
] If the value at the pointer is not zero-like, jumps to after the matching [ instruction.
, Using the value at the pointer as an index, gets an argument of the method and fills the pointed cell with it.
. Pushes the value at the pointed cell to the buffer.
/ Returns the method early; for non-void methods, whether returned early or at the end of execution, the top value of the buffer will be returned. Methods that return String will return the top value if it is a String or null, and use the whole buffer to construct a char array and then a String otherwise.
: Using the value at the pointer as an index, invokes the corresponding value from the declared brainmaps using the top of the buffer as arguments, if necessary. The cell is set to:
  • The corresponding Class object, if the index corresponds to a class.
  • The returned object, if the index is a non-void method, constructor, or field getter.
  • null, if the index is a void method or field putter.
; Invokes the super method or constructor for this method using the top of the buffer. Will always be called at least one in constructors; in constructors, the this argument will not be consumed, but is necessary in methods.

All cells start out with a value of null. All characters other than those with specific meanings are ignored; however, it is recommended to use comments for other non-alphanumeric characters, in case the syntax ever has to be expanded further. Single-line and multi-line comments work the same as in java, with // and /* ... */ respectively.