.TH "Format.Args" 3 2026-06-22 OCamldoc "OCaml library"
.SH NAME
Format.Args \- The Args module defines a heterogeneous list type, which can be used as the argument of printf-like functions.
.SH Module
Module   Format.Args
.SH Documentation
.sp
Module
.BI "Args"
 : 
.B sig end

.sp
The 
.ft B
Args
.ft R
module defines a heterogeneous list type, which can be
used as the argument of 
.ft B
printf
.ft R
\-like functions\&.
.sp
It is not required to open this module when using the functions
that accept an 
.ft B
Args\&.t
.ft R
\&. Thanks to type\-based disambiguation, the type
is inferred automatically, so the list syntax 
.ft B
[x; y; z]
.ft R
can be used
directly for heterogeneous lists\&.
.sp
An example:
.EX
.ft B
.br
\&    (* without opening Args *)
.br
\&    Format\&.lprintf "%s %d %\&.02f@\&." [ "ocaml"; 42; 3\&.14 ]
.br
\&
.br
\&    (* or with explicit construction *)
.br
\&    let lst = let open Format\&.Args in "ocaml" :: [ 42; 3\&.14 ] @ [ \&'c\&' ] in
.br
\&    Format\&.lprintf "%s %d %\&.02f %c@\&." lst
.br
\&  
.ft R
.EE

.sp
.B "Since"
5.5

.sp

.sp
.sp
.I type 
.B ('a, 'r)
.I t 
=
 | []
.B : 
.B ('r0, 'r0) t
 | (::)
.B : 
.B 'a0 * ('b, 'r1) t
.B -> 
.B ('a0 -> 'b, 'r1) t
 
.sp

.sp

.I val apply 
: 
.B 'a -> ('a, 'r) t -> 'r
.sp

.sp

.I val (@) 
: 
.B ('a, 'r1) t ->
.B   ('r1, 'r2) t -> ('a, 'r2) t
.sp

.sp