Module type
Class type

A list of pretty printers for various types, for use in toplevels.

Pretty_printer has a string list ref with the names of pp functions matching the interface:

val pp : Format.formatter -> t -> unit

The names are actually OCaml identifier names, e.g., "Base.Int.pp". Code for building toplevels evaluates the strings to yield the pretty printers and register them with the OCaml runtime.

This module is only responsible for collecting the pretty-printers. Another mechanism is needed to register this collection with the "toploop" library for pretty-printing to actually happen. How to do that depends on how you build and deploy the OCaml toplevel. One common way to do it in vanilla toplevel is to call #require "core.top".

val all : unit -> string list

all () returns all pretty printers that have been registered.

module type S = sig ... end

Modules that provide a pretty printer will match S.

module Register (M : sig ... end) : S with type t := M.t

Register builds a pp function from a to_string function, and adds the module_name ^ ".pp" to the list of pretty printers. The idea is to statically guarantee that one has the desired pp function at the same point where the name is added.

module Register_pp (M : sig ... end) : S with type t := M.t

Register_pp is like Register, but allows a custom pp function rather than using to_string.

val register : string -> unit

register name adds name to the list of pretty printers. Use the Register functor if possible.