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Metabootstrapped Messaging Protocols

This page was adapted from my recent SLE 2024 abstract submission.


Any Turing-complete bootstrapped messaging protocol can transpile its bootstrapped client to other languages. Metabootstrapping has practical advantages:

  1. Maintains consistent protocol implementations across languages.
  2. Propagates types-as-values to verify protocols at compilation time.
  3. Sufficiently powerful to propagate high-level (e.g. JSON) and low-level (e.g. TCP) protocols together.
  4. Defines unambiguous mappings between programming language features/structures.
  5. Reduces bandwidth via content-addressible "scraps".
  6. Provides a natural mechanism to check and enforce inter-program contracts.
  7. Automatically transpiles naive code from any source language to any target language.

This essay progressively enhances JSON to concretely demonstrate concepts, limitations, etc. for a more complete and thoroughly-designed implementation, see scrapscript.org.


Modern message formats (e.g. JSON, XML, gRPC) encoders/decoders must be implemented, maintained, and upgraded across all supported languages. The ambiguity of syntax and protocol in JSON and other protocols creates security threats and wastes developer time.

Basic Solution

By adding a few primitives to JSON (conditionals and simple lambdas), one can express a naive JSON parser in JSON:

  "parseJson": x =>
    parseString x
    ? parseString x
    : parseObject {} x,

  "parseString": x =>
    x == ""
    ? null
    : x[0] == "\""
      ? parseStringHelper x[1:]
      : null,

  "parseStringHelper": x =>
    x[0] == "\""
    ? ""
    : x[0] + parseStringHelper x[1:],

  "parseObject": obj => x =>
    x[0] == "{"
    ? parseObjectHelper obj x[1:]
    : null,

  "parseObjectHelper": obj => x =>
    x[0] == "}"
    ? obj
    : obj
      + parseObjectHelper
          { (parseString x): parseJson (skipKey "\"" x) }
          (skip "," (skipKey x)),

  "skip": c => x =>
    x == ""
    ? null
    : x[1] == c
      ? x[2:]
      : skipKey x[2:],

  "skipKey": x =>
    (skip ":" (skip "\"" (skip "\"" x)))


Improvements & Demonstration

The full presentation will cover examples of enhanced variations on this theme, as discovered during the development of Scrapscript.