Deadfish

Description #

Deadfish is an intentionally limited and confusing esoteric programming language with only four commands. It was designed as a joke to demonstrate how difficult a language can be while still remaining Turing complete (or nearly so). The name comes from how quickly your program can “die” if not carefully written.

History #

Deadfish was created by Jonathan Todd Skinner in the early 2000s. It became popular among esolang enthusiasts because of its quirky behavior: the accumulator never reaches 256 or -1—it resets instead. Despite its absurd limitations, people have built full logic in Deadfish as a creative challenge.

Hello World Code #

iiiiiisiiiiisiiiiisiiiiisiiiiiisiiiiiisiiiiisiiiiiisiiiiiisiiiiiisiiiiiisiiiiiisiiiiisiiiiiisiiiiiis

Each i increments the accumulator, d decrements it, s squares it, and o outputs the value.

How to Run #

Option 1: Online

• Try It Online – Deadfish

Option 2: Local

Use a Python interpreter for Deadfish:

• GitHub – Deadfish.py

Run:

python deadfish.py hello.df

Key Concepts #

• Only 4 commands:
  • i – increment
  • d – decrement
  • s – square
  • o – output
• Accumulator-based memory
• Value resets at 256 or -1
• No loops or conditionals
• Output limited to numeric ASCII
• Often used for code-golf or minimalism
• Simplicity makes writing complex logic a challenge
• Deliberate constraints encourage creativity
• “Unfriendly” design is the point
• Frequently implemented as an interpreter exercise

Try It Online #

• TIO – Deadfish

Fun Facts #

• The accumulator resets instead of overflowing or underflowing.
• Some programmers have written interpreters for Deadfish in Deadfish.
• There are dozens of unofficial variants (e.g., Deadfish~ish).

Resources #

• Deadfish on Esolangs
• TIO Deadfish Runner
• GitHub Deadfish Interpreter (Python)
• Deadfish Example Code