Module B0_std.Cmd

Command lines.

Command line values specify the command line arguments given to tool spawns. Depending on the context this may represent either only tool arguments or the full command specification with the tool to spawn as the first argument.

See examples.

Command lines

type t

The type for command lines.

A command line is a list of command line arguments. The first argument usually denotes the tool or executable to invoke.

val is_empty : t -> bool

is_empty cmd is true iff cmd is an empty list of arguments.

val empty : t

empty is an empty list of arguments.

val arg : string -> t

arg a is the atomic argument a.

val append : t -> t -> t

append cmd1 cmd2 appends arguments cmd2 to cmd1.

val unstamp : t -> t

unstamp cmd indicates that arguments cmd do not influence the tool's invocation outputs. These arguments are omitted from the command line's stamp, see stamps for more details and examples.

Derived combinators

val (%) : t -> string -> t

cmd % a is append cmd (arg a).

val (%%) : t -> t -> t

cmd1 %% cmd2 is append cmd1 cmd2.

val if' : bool -> t -> t

if' cond cmd is cmd if cond is true and empty otherwise.

val if_some : t option -> t

if_some o is cmd if o is Some cmd and empty otherwise.

val int : int -> t

int i is arg (string_of_int i).

val float : float -> t

float f is arg (float_of_int f).

val path : Fpath.t -> t

path p is arg (Fpath.to_string p).

val list : ?slip:string -> string list -> t

list ?slip l is a command line from the list of arguments l. If slip is specified it is added on the command line before each element of l.

val paths : ?slip:string -> Fpath.t list -> t

paths ?slip ps is of_list ?slip Fpath.to_string ps.

val of_list : ?slip:string -> ('a -> string) -> 'a list -> t

of_list ?slip conv l is list ?slip ( conv l).


Tools are the first argument of commands.

type tool = Fpath.t

The type for command line tools.

A command line tool is represented by a file path according to the POSIX convention for exec(3). If it is made of a single segment, for example Fpath.v "ocaml", it represents a program name to be looked up via a search procedure; for example in the PATH environment variable. If it is a file path with multiple segments (POSIX would say if they contain a slash characters) the program is the file itself.

Note. For portability one should not use the .exe suffix on Windows on tools. This should be handled transparently by tool_search procedures.

val tool : string -> t

tool t is arg t, used for reading clarity.

val find_tool : t -> tool option

find_tool cmd is cmd's first argument. This is None if the command is empty or if the first element can't be parsed to a tool.

val get_tool : t -> (tool, string) Stdlib.result

get_tool is like find_tool but returns an english Error msg on None.

val set_tool : tool -> t -> t

set_tool t cmd replaces cmd's first element with t. This is path t if cmd is empty.

The type for tool search functions.

These are functions that resolve and set the get_tool argument of commands to a concrete program executable. Or return an error message if the tool cannot be resolved. See tool_search for implementations.


val is_singleton : t -> bool

is_singleton l is true iff l has a single argument.


val fold : arg:(string -> 'a) -> unstamp:('a -> 'a) -> append:('a -> 'a -> 'a) -> empty:'a -> t -> 'a

fold ~arg ~unstamp ~append ~empty l folds over l's structure.

val iter_enc : arg:('a -> string -> unit) -> unstamp:('a -> unit) -> append:('a -> unit) -> empty:('a -> unit) -> 'a -> t -> unit
val to_list : t -> string list

to_list l converts l to a list of strings.

val to_stamp : t -> string list

to_stamp l is the sequence of stamped arguments.

val to_list_and_stamp : t -> string list * string list

to_list_and_stamp l is a l as a list of strings tuppled with its stamp: the sequence of stamped arguments.

val to_string : t -> string

to_string l converts l to a string that can be passed to the command(3) POSIX system call.

val of_string : string -> (t, string) Stdlib.result

of_string s tokenizes s into a command line. The tokens are recognized according to the token production of the following grammar which should be mostly be compatible with POSIX shell tokenization.

white   ::= ' ' | '\t' | '\n' | '\x0B' | '\x0C' | '\r'
squot   ::= '\''
dquot   ::= '\"'
bslash  ::= '\\'
tokens  ::= white+ tokens | token tokens | ϵ
token   ::= ([^squot dquot white] | squoted | dquoted) token | ϵ
squoted ::= squot [^squot]* squot
dquoted ::= dquot (qchar | [^dquot])* dquot
qchar   ::= bslash (bslash | dquot | '$' | '`' | '\n')

qchar are substitued by the byte they escape except for '\n' which removes the backslash and newline from the byte stream. squoted and dquoted represent the bytes they enclose.

val pp : t Fmt.t

pp is an unspecified formatter for commands.

val pp_dump : t Fmt.t

pp_dump formats raw dadta for debugging.


This module allows to Cmd.unstamp command arguments.

Unstamped arguments have no special semantics as far as the command line is concerned they simply indicate that the argument value itself does not influence the outputs of the tool.

Unstamped arguments do not appear in the command line stamp which is used to memoize tool spawns.

A typical example of unstamped arguments are file paths to inputs: it's often the file contents not the actual file path that determines the tool output; beware though that some tool use both the file path contents and the actual file path in their outputs. See examples.


let ls p = Cmd.(atom "ls" % "-a" % path p)
let tar archive dir =
  Cmd.(atom "tar" % "-cvf" %% unstamp (path archive) %% path dir)

let opam cmd = Cmd.(atom "opam" % cmd)
let opam_install pkgs = Cmd.(opam "install" %% list pkgs)

let ocamlc ?(debug = false) file =
  Cmd.(atom "ocamlc" % "-c" % if' debug (atom "-g") %% path file)

let ocamlopt ?(profile = false) ?(debug = false) incs file =
  let profile = Cmd.(if' profile (atom "-p")) in
  let debug = Cmd.(if' debug (atom "-g")) in
  let incs = Cmd.(unstamp (paths ~slip:"-I" incs)) in
  Cmd.(atom "ocamlopt" % "-c" %% debug %% profile %% incs %%
       unstamp (path file))