package base

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package base
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Functions for formatted output.

val ifprintf : 'a -> ('r, 'a, 'c, unit) format4 -> 'r
val sprintf : ('r, unit, string) format -> 'r
val bprintf : Caml.Buffer.t -> ('r, Caml.Buffer.t, unit) format -> 'r
val ksprintf : (string -> 'a) -> ('r, unit, string, 'a) format4 -> 'r
val kbprintf : (Caml.Buffer.t -> 'a) -> Caml.Buffer.t -> ('r, Caml.Buffer.t, unit, 'a) format4 -> 'r
Formatting error and exit functions

These functions have a polymorphic return type, since they do not return. Naively, this doesn't mix well with variadic functions: if you define, say,

let f fmt = ksprintf (fun s -> failwith s) fmt

then you find that f "%d" : int -> 'a, as you'd expect, and f "%d" 7 : 'a. The problem with this is that 'a unifies with (say) int -> 'b, so f "%d" 7 4 is not a type error -- the 4 is simply ignored.

To mitigate this problem, these functions all take a final unit parameter. These rarely arise as formatting positional parameters (they can do with e.g. "%a", but not in a useful way) so they serve as an effective signpost for "end of formatting arguments".

val failwithf : ('r, unit, string, unit -> _) format4 -> 'r

Raises Failure.

val invalid_argf : ('r, unit, string, unit -> _) format4 -> 'r

Raises Invalid_arg.