grapefizz

<-projects

bf-hs

github/>

a brainfuck interpreter written in haskell.

bf-hs

A Brainfuck interpreter written in Haskell.

overview

bf-hs is a simple and efficient Brainfuck interpreter that can execute Brainfuck programs from files or standard input. Brainfuck is an esoteric programming language with only eight commands, making it a fun challenge to implement and an interesting way to explore language interpreters.

features

  • Complete Brainfuck language support with all 8 commands
  • 30,000-cell memory tape (standard Brainfuck specification)
  • Wraparound pointer arithmetic for safe memory access
  • Interactive input/output support
  • Read programs from files or standard input
  • Clean, readable Haskell implementation

brainfuck commands

CommandDescription
>Move the data pointer to the right
<Move the data pointer to the left
+Increment the byte at the data pointer
-Decrement the byte at the data pointer
.Output the byte at the data pointer as an ASCII character
,Input a byte and store it at the data pointer
[Jump forward to the command after the matching ] if the byte at the data pointer is zero
]Jump back to the command after the matching [ if the byte at the data pointer is nonzero

installation

prerequisites

  • GHC (Glasgow Haskell Compiler)
  • Cabal build system

building from source

  1. Clone the repository:

    git clone https://github.com/grapefizz/bf-hs.git
cd bf-hs

  2. Build the project:

    cabal build

  3. Install the executable:

    cabal install

usage

running a brainfuck program from a file

bf-hs program.bf

running a brainfuck program from standard input

echo ">++++++++[<+++++++++>-]<." | bf-hs

or

bf-hs < program.bf

example

The repository includes a sample “Hello World” program in hello.bf:

bf-hs hello.bf

This should output: Hello World!

example programs

Hello World (hello.bf)

>++++++++[<+++++++++>-]<.
>++++[<+++++++>-]<+.
+++++++..
+++.
>>++++++[<+++++++>-]<++.
------------.
>++++++[<+++++++++>-]<+.
<.
+++.
------.
--------.
>>>++++[<++++++++>-]<+.

simple addition

,>,<[->+<]>.

This program reads two single-digit numbers and outputs their sum.

implementation details

  • Memory Model: Uses a 30,000-cell tape implemented with Haskell’s IOUArray
  • Pointer Wrapping: Implements wraparound arithmetic to prevent segmentation faults
  • Loop Matching: Efficient bracket matching algorithm for [ and ] commands
  • I/O Handling: Immediate character output with buffer flushing for responsive interaction

development

project structure

bf-hs/
├── app/
│   └── Main.hs          # Main interpreter implementation
├── bf-hs.cabal          # Cabal package configuration
├── hello.bf             # Example Brainfuck program
├── LICENSE              # MIT License
├── CHANGELOG.md         # Version history
└── README.md            # This file

dependencies

  • base: Core Haskell library
  • array: For efficient mutable arrays

contributing

Contributions are welcome! Please feel free to submit a Pull Request.

acknowledgments

  • Inspired by the original Brainfuck language created by Urban Müller
  • Built with the excellent Haskell ecosystem