mixing infix functions and the format4 types

mixing infix functions and the format4 types

[Anil Madhavapeddy]

Is there any way to mix infix operators with the Printf format6  
types?  I have a code printing module where this would be quite  
convenient syntactically, but the obvious attempt didn't work:

$ ocaml
         Objective Caml version 3.11.0
# open Printf;;
# let myfn m s = let xfn o = m ^ ": " ^ o in kprintf xfn s;;
val myfn : string -> ('a, unit, string, string) format4 -> 'a = <fun>
# myfn "foo" "bar";;
- : string = "foo: bar"
# myfn "foo" "%s %s" "bar1" "bar2";;
- : string = "foo: bar1 bar2"
# let (---) m s = myfn m s;;
val ( --- ) : string -> ('a, unit, string, string) format4 -> 'a = <fun>
# "foo" --- "bar";;;
- : string = "foo: bar"
# "foo" --- "%s %s" "bar1" "bar2";;
Error: This expression is not a function, it cannot be applied

Is there a trick to let this work, or do I need to stick to using non- 
infix functions for formatting?

thanks
Anil

Re: mixing infix functions and the format4 types

[Zheng Li]

Hello,

On 3/30/2009 2:18 AM, Anil Madhavapeddy wrote:
> Is there any way to mix infix operators with the Printf format6 types?
> I have a code printing module where this would be quite convenient
> syntactically, but the obvious attempt didn't work:
>
> $ ocaml
> Objective Caml version 3.11.0
> # open Printf;;
> # let myfn m s = let xfn o = m ^ ": " ^ o in kprintf xfn s;;
> val myfn : string -> ('a, unit, string, string) format4 -> 'a = <fun>
> # myfn "foo" "bar";;
> - : string = "foo: bar"
> # myfn "foo" "%s %s" "bar1" "bar2";;
> - : string = "foo: bar1 bar2"
> # let (---) m s = myfn m s;;
> val ( --- ) : string -> ('a, unit, string, string) format4 -> 'a = <fun>
> # "foo" --- "bar";;;
> - : string = "foo: bar"
> # "foo" --- "%s %s" "bar1" "bar2";;
> Error: This expression is not a function, it cannot be applied
>

Is extra separators acceptable?

# let ($) f x = f x;;
val ( $ ) : ('a -> 'b) -> 'a -> 'b = <fun>
# "foo" --- "%s %s %s" $ "bar1" $ "bar2" $ "bar3";;
- : string = "foo: bar1 bar2 bar3"

and, maybe in another way

# let (%) fmt x = Printf.sprintf fmt x;;
val ( % ) : ('a -> 'b, unit, string) format -> 'a -> 'b = <fun>
# "%s %s %s" % "bar1" $ "bar2" $ "bar3";;
- : string = "bar1 bar2 bar3"

HTH.
--
Zheng

Re: [Caml-list] Re: mixing infix functions and the format4 types

[Anil Madhavapeddy]

On 30 Mar 2009, at 10:10, Zheng Li wrote:
>
> Is extra separators acceptable?
>
> # let ($) f x = f x;;
> val ( $ ) : ('a -> 'b) -> 'a -> 'b = <fun>
> # "foo" --- "%s %s %s" $ "bar1" $ "bar2" $ "bar3";;
> - : string = "foo: bar1 bar2 bar3"

Aha ... using the identity function like this works great, thanks!

-anil

>
> and, maybe in another way
>
> # let (%) fmt x = Printf.sprintf fmt x;;
> val ( % ) : ('a -> 'b, unit, string) format -> 'a -> 'b = <fun>
> # "%s %s %s" % "bar1" $ "bar2" $ "bar3";;
> - : string = "bar1 bar2 bar3"
>
> HTH.
> --
> Zheng
>
>
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