CSCE 330 Programming Language Structures Literate Programming in Haskell

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CSCE 330Programming Language StructuresLiterate
Programming in Haskell

• Fall 2009
• Marco Valtorta
• mgv_at_cse.sc.edu

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Literate Programming

• http//www.haskell.org/haskellwiki/Literate_progra
  mming
• http//www.haskell.org/onlinereport/literate.html
• "The main idea is to regard a program as a
  communication to human beings rather than as a
  set of instructions to a computer." Donald
  Knuth
• Haskell literate programs use the .lhs extension
• Two styles Bird and LaTeX
• Hutton uses Bird style

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Example of Bird Style literate program

• The literate style encourages comments by making
  them the default. A line in which "gt" is the
  first character is treated as part of the
  program all other lines are comment.
• In Bird-style you have to leave a blank before
  the code.
• gt fact Integer -gt Integer
• gt fact 0 1
• gt fact n n fact (n-1)
• And you have to leave a blank line after the code
  as well.