Changelog

All notable changes to this project are documented in this file.

The format is based on Keep a Changelog,
and this project adheres to Semantic Versioning.

0.2.0 - 2026-07-24

Edge weights are now persistent. Each vertex's edge weights moved from a
mutable Hashtbl to a persistent map, so deriving a graph no longer mutates
any earlier version. Graph.Weights is now Map.S instead of Hashtbl.S,
and Vertex.update / Vertex.ensure now return the updated weights instead
of unit.
TreeSet re-implemented on top of Stdlib.Set. The hand-rolled
(unbalanced) BST was replaced by an adapter over Set.Make, giving
balanced-tree performance. The TSet interface is unchanged so all call sites
keep working; compare-equal inserts still replace the existing element (as the
old TreeSet did), which several algorithms rely on.

Serialize.to_dot_string and Serialize.to_dot_channel for rendering a graph
to a single dot string or straight to an out_channel, alongside the existing
lazy-sequence to_dot.
A test suite covering TreeSet, Heap, UnionFind, core Graph, the graph
algorithms (SCC, clustering, flow, path, matching, spanning trees) and dot
serialization.

add_weight no longer accumulates duplicate bindings — re-adding an edge
now replaces its weight instead of stacking entries.
MakeDisjointSet.create raises a clear Invalid_argument when the element
sequence is longer than the declared size, instead of a later out-of-bounds
crash. The unused ResolvTbl module was removed.
TreeSet no longer shadows Stdlib.Not_found, so partial operations raise
the standard exception callers can catch.
Heap consolidation table is now per-call, removing a functor-global
mutable table that could be clobbered by concurrent consolidations.
toposort now returns a valid topological (happens-before) order; it
previously emitted discovery order, which could place a successor before its
predecessor.
astar no longer raises "value not in heap"; path entries are keyed
consistently and the heap is pre-seeded, matching dijkstra's behaviour.
galeshapely now produces a stable matching; the acceptor preference
comparison was inverted, yielding blocking pairs. A leftover debug print was
also removed.

Node ids, labels and attribute values are now quoted and escaped, so arbitrary
element/weight strings (spaces, quotes, dashes, keywords) produce valid dot.
Reciprocal-edge de-duplication is applied only to undirected graphs; directed
graphs keep genuine mutual edges (A -> B and B -> A).
Attribute quoting is consistent across global, node and edge attributes, and
attribute keys are emitted in sorted order for reproducible output.
The lazy to_dot sequence is now re-forceable (no leaked mutable state), and
empty attribute brackets / redundant node declarations are avoided.