Difference between revisions of "Poor man's here document"
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BrettGiles (talk | contribs) m (Poor Man's Heredoc in Haskell moved to Poor man's here document) |
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See Also | See Also | ||
| − | [http://groups.google.de/group/fa.haskell/msg/bb29c1797fe19caf Poor Man's Heredoc, as originally posted by Claus Reinke to Haskell Cafe] | + | * [http://groups.google.de/group/fa.haskell/msg/bb29c1797fe19caf Poor Man's Heredoc, as originally posted by Claus Reinke to Haskell Cafe] |
| + | * http://en.wikipedia.org/wiki/Here_document | ||
Revision as of 08:23, 17 April 2007
main = do
doc <- here "DATA" "Here.hs" [("variable","some"),("substitution","variables")]
putStrLn doc
html <- here "HTML" "Here.hs" [("code",doc)]
putStrLn html
here tag file env = do
txt <- readFile file
let (_,_:rest) = span (/="{- "++tag++" START") (lines txt)
(doc,_) = span (/=" "++tag++" END -}") rest
return $ unlines $ map subst doc
where
subst ('$':'(':cs) = case span (/=')') cs of
(var,')':cs) -> maybe ("$("++var++")") id (lookup var env) ++ subst cs
_ -> '$':'(':subst cs
subst (c:cs) = c:subst cs
subst "" = ""
{- DATA START
this is a poor man's here-document
with quotes ", and escapes \,
and line-breaks, and layout
without escaping \" \\ \n,
without concatenation.
oh, and with $(variable) $(substitution), $(too).
DATA END -}
{- HTML START
<html>
<head><title>very important page</title></head>
<body>
<verb>
$(code)
</verb>
</body>
</html>
HTML END -}
See Also