Basically what we did for Mezzo. All printers are intended to work with 
Buffer.t and %a; then, define a bunch of variants of fprintf, iprintf, 
kprintf, sprintf, eprintf that work with Buffer.t

https://github.com/protz/mezzo/blob/master/lib/MzString.ml

On 7/8/16 3:53 AM, Gabriel Scherer wrote:
> For non-formatted printing, I find that bprintf (using Buffer.t) is 
> the more composable primitive.
>
> On Fri, Jul 8, 2016 at 4:16 AM, Rodolphe Lepigre 
> <rodolphe.lepigre@univ-savoie.fr 
> <mailto:rodolphe.lepigre@univ-savoie.fr>> wrote:
>
>     Thanks for your answer!
>
>     > I don't think this is possible with Printf.  But if you can
>     switch to Format
>     > you can use Format.asprintf instead.
>
>     Yes, I know it is possible to use Format. This is actually what I
>     am doing
>     currently! However, I am not using any of the formating features,
>     so I'd
>     like to switch to Printf to avoid going from channels to
>     formatters all the
>     time...
>
>     >> Dear list,
>     >>
>     >> If I define two values
>     >>
>     >>   val p : type out_channel -> blop -> unit
>     >>   val e : blop
>     >>
>     >> then I can do something like
>     >>
>     >>   Printf.printf "%a" p e
>     >>
>     >> but I can't find a way to do something like
>     >>
>     >>   Printf.sprintf "%a" p e
>     >>
>     >> which is not well-typed. Is there any trick that I can use to avoid
>     >> changing the type of [p] to [blop -> string]?
>     >>
>     >> Cheers,
>     >>
>     >> Rodolphe
>
>     Cheers,
>
>     Rodolphe
>     --
>     Rodolphe Lepigre
>     LAMA, Université Savoie Mont Blanc, FRANCE
>     http://lama.univ-smb.fr/~lepigre/
>     <http://lama.univ-smb.fr/%7Elepigre/>
>     On 08/07/2016 10:08, Nicolas Ojeda Bar wrote:
>
>     --
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