Module Fcommand

module Fcommand: Fcommand

This module is a wrapper around Command that allows you to do away with accumulators. Here's an example:

Fcommand.cmd ~summary:"Frobnicate something" Fcommand.( flag "-n" (required int) ~doc:"N number of times to frobnicate" ++ anon (args "item" string)) (fun n items -> ...)

type ('main_in, 'main_out) t

('main_in, 'main_out) t is a type of composable command-line specifications.

Every combinator for building t-values is polymorphic in 'main_out. In the final specification expected by cmd used to construct a command, 'main_out is specialized to unit). Various primitive specifications add parameters one at a time, so the resulting type of main is

arg1 -> ... -> argN -> unit

It may help to think of ('a, 'b) t as a function space 'a -> 'b embellished with extra information about how to parse command line, including documentation about what various flags are for.

argument parsing

type 'a parse = string -> 'a

val string : string parse

val int : int parse

val float : float parse

val date : Core.Date.t parse

val sexp : Core.Sexp.t parse

flags

module Flag: sig .. end

val required : 'a parse -> 'a Flag.t

val optional : 'a parse -> 'a option Flag.t

val optional_with_default : 'a -> 'a parse -> 'a Flag.t

val listed : 'a parse -> 'a list Flag.t

val no_arg : [ `Absent | `Present ] Flag.t

val no_arg_bool : bool Flag.t

val capture_remaining_command_line : string list option Flag.t

val flag : string -> 'a Flag.t -> doc:string -> ('a -> 'm, 'm) t

anonymous arguments

module Anons: sig .. end

val (%:) : string -> 'a parse -> 'a Anons.t

val many : string -> 'a parse -> 'a list Anons.t

val maybe : 'a Anons.t -> 'a option Anons.t

val maybe_with_default : 'a -> 'a Anons.t -> 'a Anons.t

val zero : unit Anons.t

val t2 : 'a Anons.t -> 'b Anons.t -> ('a * 'b) Anons.t

val t3 : 'a Anons.t ->
       'b Anons.t -> 'c Anons.t -> ('a * 'b * 'c) Anons.t

val t4 : 'a Anons.t ->
       'b Anons.t ->
       'c Anons.t ->
       'd Anons.t -> ('a * 'b * 'c * 'd) Anons.t

val anon : 'a Anons.t -> ('a -> 'm, 'm) t

various combinators

val empty : unit -> ('a, 'a) t

val const : 'a -> ('a -> 'm, 'm) t

val (++) : ('m1, 'm2) t -> ('m2, 'm3) t -> ('m1, 'm3) t

spec1 ++ spec2 composes command-line specifications spec1 and spec2. Parameters specified by spec1 will come before those specified by spec2 in the eventual main function.

val either : string -> ('a option -> 'b, 'a option -> 'a option -> 'b) t

val step : ('m1 -> 'm2) -> ('m1, 'm2) t

step allows you to transform the way parameters are applied. For example, if you want labelled arguments, you can do:

Fcommand.cmd ~summary:"..." Fcommand.( step (fun main x y z -> main ~x ~y ~z) ++ flag "-x" (optional string) ~doc:"..." ++ flag "-y" (required string) ~doc:"..." ++ flag "-z" (optional int) ~doc:"..." ) (fun ~x ~y ~z -> ... )

constructing the command we've specified

val cmd : summary:string ->
       ?readme:(unit -> string) ->
       ?autocomplete:Command.Autocomplete.t ->
       ?global_flags:unit Command.Flag.t list ->
       ('main, unit) t -> 'main -> Command.t