diff options
| -rw-r--r-- | stdlib/pervasives.mli | 70 |
1 files changed, 49 insertions, 21 deletions
diff --git a/stdlib/pervasives.mli b/stdlib/pervasives.mli index 7dcfdfe6f..2f93269af 100644 --- a/stdlib/pervasives.mli +++ b/stdlib/pervasives.mli @@ -883,30 +883,53 @@ external decr : int ref -> unit = "%decr" conventions. Plain characters specify string literals to be read in the input or printed in the output. - There is an additional lexical rule to escape the special characters in - format strings: if a special character follows a ['%'] character, it is - treated as a plain character. In other words, ["%%"] is considered as a - plain ['%'] and ["%@"] as a plain ['@']. + There is an additional lexical rule to escape the special characters ['%'] + and ['@'] in format strings: if a special character follows a ['%'] + character, it is treated as a plain character. In other words, ["%%"] is + considered as a plain ['%'] and ["%@"] as a plain ['@']. - For more information about conversion indications and formatting + For more information about conversion specifications and formatting indications available, read the documentation of modules {!Scanf}, {!Printf} and {!Format}. - *) (** Format strings have a general and highly polymorphic type - [('a, 'b, 'c, 'd, 'e, 'f) format6]. Type [format6] is built in. - The two simplified types, [format] and [format4] below are - included for backward compatibility with earlier releases of OCaml. - ['a] is the type of the parameters of the format, - ['b] is the type of the first argument given to - [%a] and [%t] printing functions, - ['c] is the type of the result of the [%a] and [%t] functions, and - also the type of the argument transmitted to the first argument - of [kprintf]-style functions, - ['d] is the result type for the [scanf]-style functions, - ['e] is the type of the receiver function for the [scanf]-style functions, - ['f] is the result type for the [printf]-style function. + [('a, 'b, 'c, 'd, 'e, 'f) format6]. Type [format6] is built in. The two simplified + types, [format] and [format4] below are included for backward + compatibility with earlier releases of OCaml. + + The meaning of format string type parameters is as follows: + + - ['a] is the type of the parameters of the format for formatted output + functions ([printf]-style functions); + ['a] is the type of the values read by the format for formatted input + functions ([scanf]-style functions). + + - ['b] is the type of input source for formatted input functions and the + type of output target for formatted output functions. + For [printf]-style functions from module [Printf], ['b] is typically + [out_channel]; + for [printf]-style functions from module [Format], ['b] is typically + [Format.formatter]; + for [scanf]-style functions from module [Scanf], ['b] is typically + [Scanf.Scanning.in_channel]. + + Type argument ['b] is also the type of the first argument given to + user's defined printing functions for [%a] and [%t] conversions, + and user's defined reading functions for [%r] conversion. + + - ['c] is the type of the result of the [%a] and [%t] printing functions, and + also the type of the argument transmitted to the first argument + of [kprintf]-style functions or to the [kscanf]-style functions. + + - ['d] is the type of parameters for the [scanf]-style functions. + + - ['e] is the type of the receiver function for the [scanf]-style functions. + + - ['f] is the final result type of a formatted input/output function + invocation: for the [printf]-style functions, it is typically [unit]; + for the [scanf]-style functions, it is typically the target type of the + receiver function. *) type ('a, 'b, 'c, 'd) format4 = ('a, 'b, 'c, 'c, 'c, 'd) format6 @@ -922,14 +945,19 @@ external format_of_string : literal [s]. Note: [format_of_string] can not convert a string argument that is not a literal. If you need this functionality, use the more general - {!Scanf.format_from_string} function. *) + {!Scanf.format_from_string} function. +*) val ( ^^ ) : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ('f, 'b, 'c, 'e, 'g, 'h) format6 -> ('a, 'b, 'c, 'd, 'g, 'h) format6 -(** [f1 ^^ f2] catenates format strings [f1] and [f2]. The result is a - format string that accepts arguments from [f1], then arguments from [f2]. *) +(** [f1 ^^ f2] catenates format strings [f1] and [f2]. The result is a + format string that behaves as the concatenation of format strings [f1] and + [f2]: in case of formatted output, it accepts arguments from [f1], then + arguments from [f2]; in case of formatted input, it returns results from + [f1], then results from [f2]. +*) (** {6 Program termination} *) |