A library of Functors, Monads and other category theory abstractions.

A pure computation that wraps a single value. Only useful because it
implements Functor and Monad.

A computation that can fail to produce a meaningful result; a more robust
alternative to returning a value that may be `nil`.

A two-element tuple, smaller than a vector.

A computation with an implicit context parameter. An alternative to noisy
explicit context parameters and the fragile thread locality of dynamically
bound Vars.

A computation that can fail with an error value; for when there is nothing
exceptional about getting an error and the error should be handled sooner
rather than later (or never).

A computation with an additional implicit state value that can be read and set.
Automates the threading through of immutable accumulator values etc.