diverges-on-two-sides-of-metas-that-differ.yaml

# SPDX-FileCopyrightText: Copyright (c) 2025 Objectionary.com
# SPDX-License-Identifier: MIT
---
# yamllint disable rule:line-length
# The sides of a join may be metas 'morph' bound (#1967). The join takes them
# as they are and morphs nothing again. They differ in a datum, so no join
# makes one term of them, and the firing writes 'diverged' with the metas of
# the lines that bound the two sides, instead of splitting the run (#1996).
symbolic: |
  - λ: L_fork
    dataize:
      𝛿1: $.c
    morph:
      𝑛1: $.a
      𝑛2: $.b
    join:
      on: 𝛿1
      left: 𝑛1
      right: 𝑛2
location: 'Q.y'
input: '⟦ y ↦ ⟦ c ↦ ⟦ λ ⤍ 𝜎1 ⟧, a ↦ ⟦ φ ↦ ⟦ Δ ⤍ 01- ⟧ ⟧, b ↦ ⟦ φ ↦ ⟦ Δ ⤍ 02- ⟧ ⟧, λ ⤍ L_fork ⟧.φ ⟧'
fails: "No entry of --symbolic answers the λ function 'L_fork'"
protocol: |
  𝕄(Φ.y):
    𝔼(L_fork):
      𝔻(ξ.c):
        𝛿·1·1 := 𝔻(𝜎1:λ)
      𝛿1·1 := 𝛿·1·1  # 𝔻(ξ.c)
      𝕄(ξ.a):
        morphed 𝑛·1·1 := 01-:Δ:φ
      𝑛1·1 := 𝑛·1·1  # 𝕄(ξ.a)
      𝕄(ξ.b):
        morphed 𝑛·1·2 := 02-:Δ:φ
      𝑛2·1 := 𝑛·1·2  # 𝕄(ξ.b)
      diverged 𝑛1·1 vs 𝑛2·1  # they differ at .φ.Δ, and the join names no otherwise