Module std_coverage_checklist 

Checklist: fp-library vs Rust’s std library

This document tracks the coverage of fp-library against functionality provided by Rust’s std library, mapping functional programming concepts to their standard library equivalents. It serves as a checklist for implemented features and a roadmap for future additions.

Type Classes (Traits)

FP Concept	Rust std Equivalent / Use Case	Implementation Path
Alt	Option::or, Result::or	classes/alt.rs
Alternative	Option::or, Option::xor	classes/alternative.rs
Applicative	N/A	classes/applicative.rs
ApplyFirst	N/A	classes/apply_first.rs
ApplySecond	N/A	classes/apply_second.rs
Bifoldable	N/A	classes/bifoldable.rs
Bifunctor	Result::map_err, Tuple operations	classes/bifunctor.rs
Bitraversable	N/A	classes/bitraversable.rs
Category	N/A	classes/category.rs
Choice	N/A	classes/profunctor/choice.rs
CloneFn	Clone + Fn	classes/clone_fn.rs
ClosureMode	N/A	classes/dispatch.rs
Closed	N/A	classes/profunctor/closed.rs
Cochoice	N/A	classes/profunctor/cochoice.rs
CommutativeRing	N/A	classes/commutative_ring.rs
Comonad	& (references), Box (context access)	classes/comonad.rs
Compactable	Iterator::flatten (for Option)	classes/compactable.rs
Contravariant	cmp::Ordering, Comparison functions	classes/contravariant.rs
Costrong	N/A	classes/profunctor/costrong.rs
Deferrable	Lazy evaluation	classes/deferrable.rs
DivisionRing	N/A	classes/division_ring.rs
EuclideanRing	N/A	classes/euclidean_ring.rs
Extend	N/A	classes/extend.rs
Extract	N/A	classes/extract.rs
Field	N/A	classes/field.rs
Filterable	Iterator::filter, Vec::retain	classes/filterable.rs
FilterableWithIndex	Iterator::enumerate + filter	classes/filterable_with_index.rs
Foldable	Iterator::fold	classes/foldable.rs
FoldableWithIndex	Iterator::enumerate + fold	classes/foldable_with_index.rs
Arrow	Fn (composable)	classes/arrow.rs
Functor	Iterator::map, Option::map	classes/functor.rs
FunctorWithIndex	Iterator::enumerate + map	classes/functor_with_index.rs
HeytingAlgebra	bool operations	classes/heyting_algebra.rs
LazyConfig	LazyCell, LazyLock	classes/lazy_config.rs
Lift	N/A	classes/lift.rs
LiftFn	Construction for CloneFn<Val>	classes/clone_fn.rs
Monad	Option::and_then, Result::and_then	classes/monad.rs
MonadPlus	N/A	classes/monad_plus.rs
MonadRec	N/A	classes/monad_rec.rs
Monoid	Default + Add	classes/monoid.rs
NaturalTransformation	N/A	classes/natural_transformation.rs
ParCompactable	rayon parallel compact	classes/par_compactable.rs
ParFilterable	rayon parallel filter	classes/par_filterable.rs
ParFilterableWithIndex	rayon parallel indexed filter	classes/par_filterable_with_index.rs
ParFoldable	rayon parallel fold	classes/par_foldable.rs
ParFoldableWithIndex	rayon parallel indexed fold	classes/par_foldable_with_index.rs
ParFunctor	rayon parallel map	classes/par_functor.rs
ParFunctorWithIndex	rayon parallel indexed map	classes/par_functor_with_index.rs
ParRefFilterable	rayon parallel by-ref filter	classes/par_ref_filterable.rs
ParRefFilterableWithIndex	rayon parallel by-ref indexed filter	classes/par_ref_filterable_with_index.rs
ParRefFoldable	rayon parallel by-ref fold	classes/par_ref_foldable.rs
ParRefFoldableWithIndex	rayon parallel by-ref indexed fold	classes/par_ref_foldable_with_index.rs
ParRefFunctor	rayon parallel by-ref map	classes/par_ref_functor.rs
ParRefFunctorWithIndex	rayon parallel by-ref indexed map	classes/par_ref_functor_with_index.rs
Pipe	Method chaining	classes/pipe.rs
Plus	Default (empty for Alt)	classes/plus.rs
Pointed	N/A	classes/pointed.rs
Pointer	Box, Rc, Arc	classes/pointer.rs
Profunctor	Fn(A) -> B	classes/profunctor.rs
RefApplicative	N/A (blanket)	classes/ref_applicative.rs
RefApplyFirst	N/A (blanket)	classes/ref_apply_first.rs
RefApplySecond	N/A (blanket)	classes/ref_apply_second.rs
RefCountedPointer	Rc, Arc	classes/ref_counted_pointer.rs
RefFilterable	Iterator::filter (by ref)	classes/ref_filterable.rs
RefFilterableWithIndex	N/A	classes/ref_filterable_with_index.rs
RefFoldable	Iterator::fold (by ref)	classes/ref_foldable.rs
RefFoldableWithIndex	N/A	classes/ref_foldable_with_index.rs
RefFunctor	N/A	classes/ref_functor.rs
RefFunctorWithIndex	N/A	classes/ref_functor_with_index.rs
RefLift	N/A	classes/ref_lift.rs
RefMonad	N/A (blanket)	classes/ref_monad.rs
RefPointed	N/A	classes/ref_pointed.rs
RefSemiapplicative	N/A	classes/ref_semiapplicative.rs
RefSemimonad	N/A	classes/ref_semimonad.rs
RefTraversable	N/A	classes/ref_traversable.rs
RefTraversableWithIndex	N/A	classes/ref_traversable_with_index.rs
RefWitherable	N/A	classes/ref_witherable.rs
Ring	N/A	classes/ring.rs
Semiapplicative	N/A	classes/semiapplicative.rs
Semigroup	Add	classes/semigroup.rs
Semigroupoid	N/A	classes/semigroupoid.rs
Semimonad	N/A	classes/semimonad.rs
Semiring	N/A	classes/semiring.rs
SendCloneFn	Clone + Fn + Send + Sync	classes/send_clone_fn.rs
SendDeferrable	Lazy evaluation (thread-safe)	classes/send_deferrable.rs
SendLiftFn	Construction for SendCloneFn<Val>	classes/send_clone_fn.rs
SendRefApplicative	N/A (blanket)	classes/send_ref_applicative.rs
SendRefApplyFirst	N/A (blanket)	classes/send_ref_apply_first.rs
SendRefApplySecond	N/A (blanket)	classes/send_ref_apply_second.rs
SendRefCountedPointer	Arc	classes/send_ref_counted_pointer.rs
SendRefFoldable	N/A	classes/send_ref_foldable.rs
SendRefFoldableWithIndex	N/A	classes/send_ref_foldable_with_index.rs
SendRefFunctor	N/A	classes/send_ref_functor.rs
SendRefFunctorWithIndex	N/A	classes/send_ref_functor_with_index.rs
SendRefLift	N/A	classes/send_ref_lift.rs
SendRefMonad	N/A (blanket)	classes/send_ref_monad.rs
SendRefPointed	N/A	classes/send_ref_pointed.rs
SendRefSemiapplicative	N/A	classes/send_ref_semiapplicative.rs
SendRefSemimonad	N/A	classes/send_ref_semimonad.rs
SendUnsizedCoercible	N/A	classes/send_unsized_coercible.rs
Strong	N/A	classes/profunctor/strong.rs
Traversable	Iterator::collect	classes/traversable.rs
TraversableWithIndex	N/A	classes/traversable_with_index.rs
UnsizedCoercible	N/A	classes/unsized_coercible.rs
Wander	N/A	classes/profunctor/wander.rs
Witherable	N/A	classes/witherable.rs
WithIndex	N/A	classes/with_index.rs

Not yet implemented

FP Concept	Rust std Equivalent / Use Case	Notes
Distributive	Fn(A) -> B	Dual of Traversable.
Invariant	Cell, UnsafeCell	Functors that map in both directions.
MonadError	? operator, Try trait (unstable)	Abstracts over computation that can fail.
Show	std::fmt::Display, std::fmt::Debug	Configurable string representation in FP contexts.

Data Types (Structs/Brands)

FP Data Type	Rust std Equivalent	Implementation Path
ArcBrand	std::sync::Arc	types/arc_ptr.rs
ArcCoyonedaBrand<F>	N/A	types/arc_coyoneda.rs
ArcFnBrand	Arc<dyn Fn>	types/fn_brand.rs
ArcLazy	Arc<LazyLock>	types/lazy.rs
ArcTryLazy	Arc<LazyLock<Result>>	types/try_lazy.rs
CatList	N/A	types/cat_list.rs
Const	N/A	types/const_val.rs
ControlFlow	std::ops::ControlFlow	types/control_flow.rs
Coyoneda	N/A	types/coyoneda.rs
CoyonedaExplicit	N/A	types/coyoneda_explicit.rs
Endofunction	Fn(A) -> A	types/endofunction.rs
Endomorphism	N/A	types/endomorphism.rs
FnBrand<P>	Rc<dyn Fn> / Arc<dyn Fn>	types/fn_brand.rs
Free	N/A	types/free.rs
Identity	convert::identity	types/identity.rs
Option	Option	types/option.rs
Pair	(A, B)	types/pair.rs
RcBrand	std::rc::Rc	types/rc_ptr.rs
RcCoyonedaBrand<F>	N/A	types/rc_coyoneda.rs
RcFnBrand	Rc<dyn Fn>	types/fn_brand.rs
RcLazy	Rc<LazyCell>	types/lazy.rs
RcTryLazy	Rc<LazyCell<Result>>	types/try_lazy.rs
Result	Result	types/result.rs
SendEndofunction	Arc<dyn Fn(A) -> A>	types/send_endofunction.rs
SendThunk	N/A	types/send_thunk.rs
String	String	types/string.rs
Thunk	N/A	types/thunk.rs
Trampoline	N/A	types/trampoline.rs
TrySendThunk	N/A	types/try_send_thunk.rs
TryThunk	N/A	types/try_thunk.rs
TryTrampoline	N/A	types/try_trampoline.rs
Tuple1	(A,)	types/tuple_1.rs
Tuple2	(A, B)	types/tuple_2.rs
Vec	Vec	types/vec.rs

Not yet implemented

FP Data Type	Rust std Equivalent	Notes
BinaryHeapBrand	std::collections::BinaryHeap	Priority queue.
BoxBrand	std::boxed::Box	Fundamental smart pointer.
BTreeMapBrand	std::collections::BTreeMap	Sorted key-value store.
BTreeSetBrand	std::collections::BTreeSet	Sorted set.
HashMapBrand	std::collections::HashMap	Key-value store.
HashSetBrand	std::collections::HashSet	Set of unique values.
IO	main, std::fs, std::net	Encapsulates side effects.
LinkedListBrand	std::collections::LinkedList	Doubly-linked list.
Reader	Function arguments, std::env	Encapsulates dependency injection.
State	let mut, RefCell	Encapsulates stateful computations.
Validation	Result (but accumulating)	Similar to Result, but collects all errors.
VecDequeBrand	std::collections::VecDeque	Double-ended queue.
Writer	std::io::Write, Logging	Encapsulates logging or accumulating side outputs.

Helper Wrappers (Newtypes)

Wrapper Type	Rust std Equivalent	Implementation Path
Additive	std::iter::Sum (trait)	types/additive.rs
Conjunctive	bool AND	types/conjunctive.rs
Disjunctive	bool OR	types/disjunctive.rs
Dual	std::cmp::Reverse	types/dual.rs
Endofunction	Fn(A) -> A	types/endofunction.rs
Endomorphism	N/A	types/endomorphism.rs
First	Option::or	types/first.rs
Last	Option (overwrite)	types/last.rs
Multiplicative	std::iter::Product (trait)	types/multiplicative.rs

Not yet implemented

Wrapper Type	Rust std Equivalent	Notes
Max	std::cmp::max	Semigroup that takes the maximum value.
Min	std::cmp::min	Semigroup that takes the minimum value.

Free Functions

Function	Rust std Equivalent	Implementation Path
compose	N/A	functions.rs
constant	N/A	functions.rs
flip	N/A	functions.rs
identity	std::convert::identity	functions.rs
on	N/A	functions.rs
pipe	Method chaining	classes/pipe.rs

All type class free functions (map, bind, pure, fold_map, traverse, etc.) are defined in their respective trait modules under classes/ and re-exported via functions.rs.

Summary of Priorities

1. Collections: Adding brands for HashMap, HashSet, BTreeMap, and Box would immediately widen the library’s utility for standard Rust applications.
2. Error Handling: Validation (accumulating Result) is high-value for robust error handling and would enable the ParTraversable error-accumulation flavour.
3. Extensible Effects: State, Reader, and Writer are planned as effects within an extensible effects system rather than standalone monads. See effects plan.