Traversable (travesty.Travesty.Traversable)

Signatures

For input and output module signatures for this module's functors, see Traversable_types.

Making traversable containers

Monadic traversal is sufficient to define fold, and, therefore, all of the key functionality for a Base-style container. As such, our signatures and functors subsume those for building containers.

New containers

module Make0
  (I : Traversable_types.Basic0) : 
  Traversable_types.S0 with module Elt = I.Elt and type t = I.t

Make makes an S0 from a Basic0.

module Make1
  (I : Traversable_types.Basic1) : 
  Traversable_types.S1 with type 'a t = 'a I.t

Make makes an S1 from a Basic1.

Extending existing containers with monadic traversals

module Make0_container
  (I : Traversable_types.Basic0_container) : 
  Traversable_types.S0 with module Elt = I.Elt and type t = I.t

Make0_container makes an S0 from a Basic0_container.

module Make1_container
  (I : Traversable_types.Basic1_container) : 
  Traversable_types.S1 with type 'a t = 'a I.t

Make1_container makes an S1 from a Basic1_container.

Combining and modifying traversable containers

Chaining

module Chain0
  (Outer : Traversable_types.S0)
  (Inner : Traversable_types.S0 with type t := Outer.Elt.t) : 
  Traversable_types.S0 with module Elt = Inner.Elt and type t = Outer.t

Chain0 chains two S0 instances together, traversing each element of the outer instance with the inner instance.

Fixing the element type

module Fix_elt
  (I : Traversable_types.S1)
  (Elt : Base.Equal.S) : 
  Traversable_types.S0 with module Elt = Elt and type t = Elt.t I.t

Fix_elt (I) (Elt) demotes an S1 S to an S0 by fixing the element type to that mentioned in Elt.

Helper functions and functors

module Const
  (T : Base.T)
  (Elt : Base.Equal.S) : 
  Traversable_types.S0 with module Elt = Elt and type t = T.t

Const constructs a S0 over container T and arbitrary element type Elt that, when traversed, makes no calls to the supplied function and returns the container unchanged.