percent-format

simple printf-style string formatting for Haskell

Monthly Downloads: 20

Programming language: Haskell

License: BSD 3-clause "New" or "Revised" License

Tags: Testing    

README

PercentFormat -- C-like printf-style string formatting for Haskell

The Text.PercentFormat library provides printf-style string formatting. It provides a % operator (as in Ruby or Python) and uses the old C-printf-style format you know and love.

This library differs from Text.Printf in that it does not rely on custom typeclasses -- it works on anything that is a Show instance.

Formatting one value:

> import Text.PercentFormat
> "Hello %s!" -% "World"
"Hello World!"

Formatting three values, tuple style, using -%%%:

> "load average: %1.2f %1.2f %1.2f" -%%% (0.00, 0.066, 0.11)
"load average: 0.00 0.07 0.11"

Formatting three values, chain style, using % and -%:

> "load average: %1.2f %1.2f %1.2f" % 0.00 % 0.066 -% 0.11
"load average: 0.00 0.07 0.11"

To produce a string with a percent sign (%), use two percent signs (%%):

> "memory usage: %i%%" -% 13
"memory usage: 13%"

Percent signs are duplicated when using the % operator to allow chaining:

> "percent sign: %s, memory usage: %i%%" % "%" % 87
"percent sign: %%, memory usage: 87%%"

Always use the -% operator when formatting the last value to remove duplicate % signs:

> "percent sign: %s, memory usage: %i%%" % "%" -% 87
"percent sign: %, memory usage: 87%"

To print, just prefix you format expression with putStrLn $:

> putStrLn $ "Hello %s!" -% "World"
Hello World!

For more information and a detailed list of options, see PercentFormat's Haddock Documentation.

PercentFormat is a work in progress. Any help or pull requests are welcome. See [PercentFormat's TO DO list] for ideas on how to contribute.

Installing

To install the latest PercentFormat version from Hackage, just run:

$ cabal update
$ cabal install percent-format