printf-mauke-0.5.3: A Perl printf like formatter.

Safe HaskellSafe-Inferred

Text.Printf.Mauke

Synopsis

Documentation

printf :: PrintfType r => String -> rSource

Format a variable number of arguments according to a format string, similar to (s)printf in Perl. The return value is either a String or IO a, in which case the result is printed to stdout. If you use the IO variant, don't use the result: Because it has to be of any type a, this library makes it undefined.

The format string consists of ordinary characters (everything except '%'), which are passed through unchanged, and formatting directives, which have the following form: 

  % flag* vector? width? precision? type

(* and ? mean 0 or more and 0 or 1 of the preceding item, respectively.)

Flags:

space
prefix positive numbers with a space
+
prefix positive numbers with a plus sign (overrides space if both are present)
-
left-justify within the field
0
pad with zeroes on the left, not spaces
#
prefix binary numbers with 0b/0B, octal numbers with 0o/0O and hexadecimal numbers with 0x/0X

The vector flag v tells printf to format each character in the string argument according to the current directive, then joins the results with a separator that defaults to ".". When *v is used, the separator is taken from the argument list (use e.g. printf "%*v.2x" "" str if you want no separator).

The width is either a decimal integer or *, in which case the width is taken from the argument list (this argument must be an integer). It specifies the minimum width for this field. Shorter values are padded on the left with spaces (but this can be changed by the 0 and - flags). If the width taken from the argument list is negative, it behaves as if the - flag was specified.

The precision consists of a . followed by digits or a * (see the description of width above). The effects depend on the format type:

  • for floating point formats, this specifies the number of digits after the decimal point
  • for string formats, this is the maximum number of characters to appear (longer strings are truncated)
  • for integer formats, this is the minimum number of digits to appear in the output; shorter values are zero-padded

Types:

%
A percent sign. No argument is consumed.
c
A character. If the argument is an integer, it is converted with chr.
s
A string.
d
A decimal integer.
u
An unsigned decimal integer.
b
A binary integer.
B
Like b, but using a 0B prefix with #.
o
An octal integer.
O
Like o, but using a 0O prefix with #.
x
A hexadecimal integer.
X
Like x, but using uppercase letters.
e
A floating point number in scientific notation.
E
Like e, but using an uppercase E.
f
A floating point number in fixed decimal notation.
g
A floating point number in %e or %f notation.
G
Like g, but using an uppercase E.
_
A generic format; it behaves like %c, %s, %d or %g, depending on the argument type.

hPrintf :: HPrintfType r => Handle -> String -> rSource

Like printf, except that the result is printed to the specified Handle.

class PrintfArg a whereSource

Class for valid printf arguments.

Methods

embed :: a -> ArgSource

Instances

data Arg Source

The internal type used to wrap and store all arguments.

Constructors

AInt Integer 
AChar Char 
AStr String 
AFloat Double 

Instances

class FromChar a whereSource

Methods

fromChar :: Char -> aSource

Instances

class ToChar a whereSource

Methods

toChar :: a -> CharSource

Instances

class PrintfType a Source

Instances

FromChar a => PrintfType [a] 
PrintfType (IO a) 
(PrintfArg a, PrintfType r) => PrintfType (a -> r) 

class HPrintfType a Source

Instances

HPrintfType (IO a) 
(PrintfArg a, HPrintfType r) => HPrintfType (a -> r)