Module PatMapSharing.SharingSource

Comparisons with sharing. Sharing.equal eq and Sharing.compare cmp return the same results as equal eq and compare cmp, but as a side effect they make the equal subtrees of their arguments physically equal. Later comparisons of these maps are then faster, and duplicate subtrees can be reclaimed. A subtree is replaced with one whose values are related by eq (or cmp returns 0): use these functions only when such values are interchangeable, for instance with a structural equality. This is invisible to the other operations and safe with concurrent domains.