Easy and type-safe format strings for parsing and printing

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LTS Haskell 13.7:
Stackage Nightly 2019-02-17:
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MIT licensed by Li-yao Xia
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Module documentation for

Haskell scanf Build Status

A lightweight library for one-off parsing and printing.

scanf [fmt|%d lazy %s and %d strict %s|]
      "3 lazy functions and 2 strict fields"
  = Just (3 :+ "functions" :+ 2 :+ "fields" :+ ())

Quasiquotes are optional. Format strings can also be defined with pure Haskell combinators.

printf (fmt_ (int . " lazy " % string . " and " % int . " strict " % string)
       (8 :+ "dogs" :+ 9 :+ "cats" :+ ())
  = "8 lazy dogs and 9 strict cats"

With quasiquotes, the following conversion strings are supported:

  • %d: signed integer (Int)
  • %l: signed integer (Integer, unbounded)
  • %f: floating point (Double)
  • %s: string of non-space characters (String)
  • %c: single character (Char)
  • %%: parse/print a literal percent character

N.B.: in scanf, spaces in the format string match any number of whitespace character until the next nonspace character.

Though it also offers a printf function, scanf is thus named as there are only few other preexisting Haskell implementations, whereas many Haskell printf libraries can already be found on Hackage.

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Depends on 2 packages:
Used by 1 package:
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