fires-a-sibling-once-through-a-dispatch-into-its-object.yaml

# SPDX-FileCopyrightText: Copyright (c) 2025 Objectionary.com
# SPDX-License-Identifier: MIT
---
# yamllint disable rule:line-length
# The term at 'Φ.e' reads 'φ' of the object 'Φ.same' makes, and that 'φ'
# reads its sibling 'm' twice. Before #1727 the head pass of 𝕄 copied 'm'
# into both reads before anything fired, so the deep walk later fired
# 'L_dataized' again for each copy, four firings in all. Now, under '--deep',
# the head pass first fires the reads of siblings in the binding it
# dispatches into, the way the deep walk fires them, and writes their answers
# back, so 'm' fires once and both reads take its answer: two firings, as
# many as the same object costs without the '.φ'.
symbolic: |
  - λ: L_bytes_eq
    dataize:
      𝛿1: $.ρ
      𝛿2: $.b
    𝑛: Φ.bytes( φ ↦ ⟦ λ ⤍ 𝜎 ⟧ )
  - λ: L_dataized
    dataize:
      𝛿1: $.target
    𝑛: Φ.bytes( φ ↦ ⟦ λ ⤍ 𝜎 ⟧ )
location: 'Q.e'
deep: true
partial: true
acyclic: plausible
input: >
  ⟦ bytes(φ) ↦ ⟦ eq(ρ, b) ↦ L_bytes_eq:λ ⟧,
    dataized(target) ↦ L_dataized:λ,
    same(left) ↦ ⟦ φ ↦ m.eq( b ↦ m ), m ↦ Φ.dataized( target ↦ left ) ⟧,
    e ↦ Φ.same( left ↦ Φ.bytes( φ ↦ 𝜎1:λ ) ).φ ⟧
result: '⟦ φ ↦ 𝜎3:λ, eq(b) ↦ L_bytes_eq:λ ⟧'
protocol: |
  𝕄(Φ.e):
    𝑛·0·1 := Φ.same( left ↦ Φ.bytes( φ ↦ 𝜎1:λ ) )
    𝑛·0·2 := Φ.dataized( target ↦ Φ.bytes( φ ↦ 𝜎1:λ ) )
    𝔼(L_dataized):
      𝔻(Φ.a🌵0):
        𝕄(Φ.a🌵0):
          𝑛·1·1 := Φ.bytes( φ ↦ 𝜎1:λ )
      𝛿1·1 := 𝔻(𝜎1:λ)  # 𝔻(ξ.target)
      𝑛·1·2 := Φ.bytes( φ ↦ 𝜎2:λ )  # 𝑛
      𝕄(𝑛·1·2):
        𝑛·1·3 := Φ.bytes( φ ↦ 𝜎2:λ )
      𝑛·1·4 := 𝑛·1·3  # 𝕄(𝑛·1·2)
    𝑛·0·3 := 𝑛·1·3.eq( b ↦ 𝑛·1·3 )
    𝔼(L_bytes_eq):
      𝔻(Φ.a🌵1):
        𝕄(Φ.a🌵1):
          𝑛·2·1 := Φ.bytes( φ ↦ 𝜎2:λ )
      𝛿1·2 := 𝔻(𝜎2:λ)  # 𝔻(ξ.ρ)
      𝛿2·2 := 𝔻(𝜎2:λ)  # 𝔻(ξ.b)
      𝑛·2·2 := Φ.bytes( φ ↦ 𝜎3:λ )  # 𝑛
      𝕄(𝑛·2·2):
        𝑛·2·3 := Φ.bytes( φ ↦ 𝜎3:λ )
      𝑛·2·4 := 𝑛·2·3  # 𝕄(𝑛·2·2)