Index module used to index elements in the store

Type of stores

The empty store

is_empty s

• returns

  true if s is empty, false otherwise.

cardinal s

• returns

  the number of elements in s.

next_ix s

• returns

  the next index the store s will use to index a new element.

singleton el

• returns

  the tuple (ix, store), where ix is the index under which the only element el was stored, and store is the store containing el.

add el s

• returns

  the tuple (new_ix, new_store), where new_ix is the index under which the new element el was stored, and new_store is the new store containing el.

find ix s

• returns

  the element stored under index ix.

• raises Not_found

  if index ix not bound.

update ix el s rebinds index ix in store s to point to el, and returns the resulting store. The previous binding disappears. New indices resulting from further adds are guaranteed to have higher indices.

• raises Not_found

  if index ix not bound.

remove ix s removes the binding of index ix of store s, and returns the resulting store.

iter f s applies f to all stored elements in store s. The order in which elements are passed to f is unspecified.

iter f s applies f to all indexes and their related elements in store s. The order in which elements are passed to f is unspecified.

map f s

• returns

  a store with all elements in s mapped from their original value to the codomain of f. Only the elements are passed to f. The order in which elements are passed to f is unspecified.

mapi f s same as map, but function f also receives the index associated with the elements.

fold f s a computes (f eN ... (f e1 a) ...), where e1 ... eN are the elements of all bindings in store s. The order in which the bindings are presented to f is unspecified.

foldi f s a same as fold, but function f also receives the index associated with the elements.

to_list s converts s to an association list of indices and elements.

choose s

• returns

  a tuple (ix, x), where ix is the index of some unspecified value x in store s.

• raises Not_found

  if s is empty.

filter p s

• returns

  the store of all elements in s that satisfy p.

partition p s

• returns

  a pair of stores (s1, s2), where s1 is the store of all the elements of s that satisfy the predicate p, and s2 is the store of all the elements of s that do not satisfy p.

eq_classes eq s

• returns

  a list of tuples (el, ec), where el is the only kind of element as identified by the equivalence relation eq stored in the equivalence class (store) ec under each index. Every such equivalence class is unique and maximal with respect to s, and the original indices of the elements are preserved in each class.

get_ix_map s

• returns

  a map of all indices mapped to their respective elements in store s.