diff options
Diffstat (limited to 'lib/rites/rite_ef/lectionary_ef.ml')
| -rw-r--r-- | lib/rites/rite_ef/lectionary_ef.ml | 57 |
1 files changed, 55 insertions, 2 deletions
diff --git a/lib/rites/rite_ef/lectionary_ef.ml b/lib/rites/rite_ef/lectionary_ef.ml index ec1aa0a..02c3c64 100644 --- a/lib/rites/rite_ef/lectionary_ef.ml +++ b/lib/rites/rite_ef/lectionary_ef.ml @@ -2,6 +2,10 @@ open Colitur_kernel (* Step 1: the observed celebration's own proper. Step 2: the day's own temporal slug. + Step 3: a weekday whose own slug has no entry says the preceding Sunday's + Mass -- see the implementation comment on that branch in [readings] for + the termination argument and why it is the Sunday's TEMPORAL, not + observed, identity. Nothing here encodes "Lent has daily propers": the presence of an entry in [lectionary] is the sole discriminator -- this function does not branch on @@ -17,10 +21,59 @@ open Colitur_kernel ferial-Mass rubrics when coding") -- that confirmation has not been done; do not read this comment as citing RG/the Missal for the SELECTION rule itself, only [Lectionary.find]'s presence-or-absence as the mechanism. *) -let readings ~lectionary ~observed ~temporal ~date:_ ~temporal_at:_ = +(* Days from a given weekday back to the preceding Sunday. Sunday itself + yields 0, which is why step 3 must guard on it -- see [readings] below. *) +let days_since_sunday : Date.weekday -> int = function + | Date.Sun -> 0 + | Date.Mon -> 1 + | Date.Tue -> 2 + | Date.Wed -> 3 + | Date.Thu -> 4 + | Date.Fri -> 5 + | Date.Sat -> 6 + +let readings ~lectionary ~observed ~temporal ~date ~temporal_at = match observed.Celebration.citations with | _ :: _ as cs -> cs | [] -> ( match Lectionary.find lectionary temporal.Temporal.office.Celebration.slug with | Some cs -> cs - | None -> []) + | None -> ( + (* Step 3: a feria with no proper of its own says the preceding + Sunday's Mass. WARRANT is the same as step 2's -- lectio's own + observed behaviour, not a confirmed Missal citation: this is the + rule lectio hard-codes as data on the four Advent ferias + (Advent II's readings copied verbatim onto the following + Monday-Saturday) and leaves absent on the other slugs this step + now also reaches; docs/research/rules-register.md already + records the ferial-Mass selection rule itself as unconfirmed + against the primary source. + + Termination: guarded on weekday. A Sunday reaching this branch + would compute [days_since_sunday Sun = 0] and look up ITSELF, + looping forever -- every other step in the chain consults data + (a lectionary lookup), this is the only one that consults + another date, so this guard is the whole chain's termination + argument, not merely a special case. + + The preceding Sunday's TEMPORAL slug, never its observed one: + the rubric is the preceding Sunday's Mass even in a year when a + feast displaced that Sunday from being observed (see + test_step3_uses_temporal_not_observed). [temporal_at] gives the + temporal identity of any date, so the Sunday is reached by date + arithmetic and a fresh call to the temporal cycle -- never by + string surgery on [own_slug]: the slug shapes are genuinely + inconsistent across seasons (e.g. [ef-advent-sunday-1] versus + [ef-advent-1-monday], the week number on opposite sides of the + season name), so deriving one from the other textually would be + a latent bug the moment a season's naming convention differs. *) + let offset = days_since_sunday temporal.Temporal.weekday in + if offset = 0 then [] + else + let sunday = Date.add_days date (-offset) in + let sunday_temporal = temporal_at sunday in + match + Lectionary.find lectionary sunday_temporal.Temporal.office.Celebration.slug + with + | Some cs -> cs + | None -> [])) |