mathlib-duck

The groupant beside tools/mathlib/src/duck.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.

Facts

Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.

Components

component	label	where
approximant	partial	approximant
ast	partial	`syntax.json`
cost	partial	invariant-and-cost
descriptant	present	descriptant
invariant	partial	invariant-and-cost
tests	bounded checks	tests

Obernants

The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.

id	type	label	where
`behavior_complement`	behavior_complement	partial source derived model	behavior_complement
`reverse_reconstruction`	reverse_reconstruction	partial source derived model	reverse_reconstruction
`substitution_order`	substitution_order	partial source derived model	substitution_order
`quote_transport`	quote_transport	partial source derived model	quote_transport
`failure_precedence`	failure_precedence	partial source derived model	failure_precedence
`lossy_output_decode`	lossy_output_decode	partial source derived model	lossy_output_decode

Model text

descriptant

mathlib-duck

run selects DUCKDB or HOME/bin/duckdb, spawns -bail -batch plus optional mode and db, writes SQL then waits; nonzero status or stderr Error: returns error, otherwise stdout is decoded lossily. fill folds ordered global replacements after doubling apostrophes.

Epoch 2026-10-31

Prospective model retained before changes. Existing production bytes are preserved; additions are bounded inline tests. Nine source groupants expose ingestion and routing boundaries; typed children bind exact source bytes and reuse their parent syntax projection. Native tests run twice per profile; behavior mutants run as compiled source changes and exact bytes are restored before positive checks.

Important retained observation: network-looking helpers are not all pure (DNS inside github_host and books build); selection deliberately excludes those effects. Mixed-format manifest order is not deterministic, and error paths do not imply rollback.

No network/DNS/download, real catalog/corpus/model/teacher or database execution. Effect paths are source-derived; finite helper tests are not universal verification. No executable percentage surrogate or speed claim; future caps require metric/domain/reference and remain 1/2/5/10%.

approximant

Forward relation

Model observations include returns, retained state and ordered partial effects; on external failures the successful-prefix relation replaces a total-function claim.

Composition

Scoped children isolate the declared contiguous source intervals. Their operations compose only where the source calls them; costs of overlapping parent/child descriptions are not added twice. Remaining effect paths retain explicit gaps.

catalog

behavior_complement

Subject: mathlib-duck, source SHA-256 9f7321a7f368a542a2a9cb3bd2c79adf590517f4d6a0c7b88c7adf254bac7946; finite transition observation.

If spawn fails, no SQL is written to a child by this call. If status is failure or stderr contains exact Error:, wrapper cannot return Ok(stdout). No claim that every DB failure uses that marker.

Domain: stated source predicates, bounded inputs and available resources; arithmetic assumptions and external effect gaps as in the invariant. Operator is the stated relation/projection; complement is a source-derived inner exclusion, reverse retains compatible antecedents. Other views are source-derived partial constraints, not inverse laws.