Language of the Month for April 2018: Brain-Flak

Question

In accordance with our meta agreement to have a Language of the Month, and since the list of nominations has a single highest-voted entry as March nears its end, I am pleased to announce the next featured language! Throughout April 2018, our Language of the Month, nominated by Destructible Lemon, will be:

Brain-Flak

What's a Language of the Month?

See the meta posts linked above. In short, during April, those who wish to participate should learn (at least the basics of) Brain-Flak, use it to solve challenges, and discuss it in the Brain-Flak chat room, The Third Stack. Participation is completely optional, but is anticipated to be fun!

Information about Brain-Flak

Brain-Flak is a minimalist stack-based turing tarpit. It uses only the brace characters ()[]{}<>, which must be balanced. Data consists of integers stored on a pair of stacks. However, despite its humble feature set, there is a surprising depth and elegance to the language.

• Brain-Flak is entirely composed of atoms, which can either be niladic (taking 0 arguments) or monadic (taking exactly one argument). A nilad is a pair of brackets with nothing between them, i.e. one of "()", "{}", "[]", or "<>". A monad is a pair of brackets with any number of other atoms between them.

  Due to the nature of using only brackets for code, these atoms are highly nestable. One of the most fun pieces of using brain-flak is learning how to use these atoms efficiently for both their functionality and returned value.

• Even though it was designed as a turing tarpit with only 8 commands, there are certain tasks that can done very tersely in brain-flak. Most notably, operations with polygonal numbers and summations.

Documentation

The readme on the GitHub repository contains a good summary of the language. Further help can be found at:

• Brain-Flak wiki on GitHub
• Esolangs.org page
• Tips question

• The Third Stack chat room

  For help, you can ping @DJMcMayhem or @user56656.

  (If you consider yourself knowledgeable in brain-flak and would like to help teach it to other users, feel free to add your name to the list)

Interpreter

The simplest way to run Brain-Flak is through Try It Online! There are two interpreters available on TIO: the original Ruby interpreter and an implementation in Haskell.

You can also download implementations in Ruby, C, Haskell, and Prolog.

---

(([((((()()())()())({}){}))]((((([]([][]([[]]([[]()()]([][]()([]()({}{}{})({})({})))))))[[]()])<([][][][])>[][])()[[]])))[[][]]())

^{Thanks to Jo King, user56656, and Nitrodon for golfing help :D}

Answer 1

List of all Brain-Flak solutions posted in April

• 1, 2, Fizz, 4, Buzz by Jo King
• Arbitrary-length currying by BMO
• Color count, sorted by occurences by Kamil Drakari
• Expand Compressed Brain-Flak by Jo King
• Expand Compressed Brain-Flak by Kamil Drakari
• Generate Men of Culture by Kamil Drakari
• How many arguments were passed? by BMO
• Magic the Gathering: Friends or Foes? by Jo King
• Magic the Gathering: Friends or Foes? by Nitrodon
• Make an Emergency Corridor by Jo King
• Print the Previous Answer by Jo King
• Same length, different string by Jo King
• Up go the bits! by MegaTom
• Output some reserved word by Jo King
• Output some reserved word by DJMcMayhem
• Scrabble scorer by DJMcMayhem

• Seidel Triangle by Nitrodon

• add entries in the form:

  [<challenge title>](https://codegolf.stackexchange.com/a/<answer-ID>) by [username](https://codegolf.stackexchange.com/users/<user-ID>)
  

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List of all Brain-Flak tips posted in April

• Check your negatives by Jo King

• add entries in the form:

  [<tip title>](https://codegolf.stackexchange.com/a/<answer-ID>) by [username](https://codegolf.stackexchange.com/users/<user-ID>)
  

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List of Brain-Flak-related challenges posted in April

• Expand Compressed Brain-Flak by DJMcMayhem

• add entries in the form:

  [<challenge title>](https://codegolf.stackexchange.com/q/<question-ID>) by [username](https://codegolf.stackexchange.com/users/<user-ID>)