Tagless Encodings

Tagless encodings may be specified by encoding tags in template placeholders and in tagless-element sequences. In binary, this allows the opcode to be elided from the encoding of values that fill tagless slots.

Consider the following data:

[
  { sum: 123, sample_count: 12 },
  { sum:  54, sample_count:  8 },
  { sum: 125, sample_count: 15 },
  { sum: 314, sample_count: 30 },
]

With a macro such as (metric {sum: (:? {#int}), sample_count: (:? {#int}), unit: ms}), it can be encoded more compactly:

[
  (:metric 123 12),
  (:metric  54  8),
  (:metric 125 15),
  (:metric 314 30),
]

We can increase the compactness even more using a tagless-element list as follows:

[{:metric} // {:<macro_name>} specifies a macro-shape
  (123 12),
  ( 54  8),
  (125 15),
  (314 30),
]

Both primitive and macro-shape encodings may be used in tagless-element sequences; only the primitive encodings in the below table may be used in tagless template placeholders.