esotope plan

This design document obsoletes the prior esotope IL plan.

Notes

• Languages are roughly divided into several categories:
  • Finite automaton
  • Tape-based imperative (Spaghetti?)
  • Stack-based imperative (Whitespace etc.)
  • Queue-based imperative
  • Heap-based imperative
  • Tape-based structured (Brainfuck etc.)
  • Stack-based structured (Kipple etc.)
  • Queue-based structured (Aheui is a hybrid example of stack/queue-based structured languages)
  • Heap-based structured (LOLCODE etc.)
  • Functional with an (primarily) eager evaluation (Unlambda etc.)
  • Functional with a lazy evaluation (LazyK etc.)
  • String rewriting (Thue etc.)
  • Self-repeating (NULL, Fractran etc.)
  • Self-modifying (INTERCAL, Muriel etc.)
  • Multi-dimensional with no wrapping (Orthogonal etc.)
  • Multi-dimensional with wrapping
  • Multi-dimensional self-modifying with no wrapping
  • Multi-dimensional self-modifying with wrapping (Befunge93 etc.)
  • Assembly (Malbolge etc.)
  • Non-esolang for inputs
  • Non-esolang for outputs (C, BASIC etc.)
  • etc.
• The internal representation no longer generalizes the category, however. Only the translators between languages imply the cluster of languages.
• One language may have several internal representations. (Befunge93, Befunge93NoWrap, Befunge93Static etc.)
• One internal representation may fit for many languages. (Ook and Unary shares the same representation as Brainfuck)
• The internal representation is not necessarily correlated to the language. (internal representations for Befunge93 may include a program with non-standard Funge space size like 40x50, for example)

Not sure

• I/Os should be decoupled, but how? The catch-all I/O interface might not be enough. (e.g. how to handle the division by zero in Befunge93?) Ocaml’s lack of safe downcasting complicates the design here.
• “Optimization” weight for translators.

Hierarchy

• Text
  • HQ9plus
    • HQ9plusplus
• Brainfuck (Brainfuck code + possible predefined input)
  • Ook
  • BFRLE (+*40 etc.)
  • Spoon (Brainfuck with an immediate exit)
    • SpoonWithLocations (Brainfuck/Spoon with implicit locations; e.g. temp0++temp1-- should return something like ++<-- which minimizes movements.)
• Glass

• Kipple

• Befunge93 (returns arbitrarily sized Funge space, not only 80x25)
  • Befunge93Nowrap
    • Befunge93Static (statically compilable subset of Befunge–93, possibly with a Funge space larger than 80x25)
    • Orthogonal, Orthagonal
      • OrthogonalStatic
  • Funge98

• PATH

• ETA

• Shakespeare

• Unlambda (with Extern node for FFI-like things)
  • Grass
  • Underload (the reversal is not simple, though)

• LazyK

• Minus

• Malbolge