Immanuel Litzroth <[EMAIL PROTECTED]> writes:
> I have a small question relating to literate haskell programs that
> use the \begin{code} \end{code} style. Am I correct to assume that
> \end{code} inside a string should be recognized as being inside a
> string. The report seems to say this, but the unlit that is
> distributed with ghc doesn't grok this. Has anyone written an Unlit
> module in Haskell?
I have attached the Unlit.hs module from the nhc98 compiler, based
on the original specification in the the Haskell 1.2 Report. Use the
exported function
unlit :: String -> String -> String
whose first argument is the filename (for error messages), the second
argument is the file content, and whose result is the un-literated
file.
Regards,
Malcolm
module Unlit(unlit) where
-- Part of the following code is from
-- "Report on the Programming Language Haskell",
-- version 1.2, appendix C.
import Char
data Classified = Program String | Blank | Comment
| Include Int String | Pre String
classify :: [String] -> [Classified]
classify [] = []
classify (('\\':x):xs) | x == "begin{code}" = Blank : allProg xs
where allProg [] = [] -- Should give an error message,
-- but I have no good position information.
allProg (('\\':x):xs) | x == "end{code}" = Blank : classify xs
allProg (x:xs) = Program x:allProg xs
classify (('>':x):xs) = Program (' ':x) : classify xs
classify (('#':x):xs) = (case words x of
(line:file:_) | all isDigit line
-> Include (read line) file
_ -> Pre x
) : classify xs
classify (x:xs) | all isSpace x = Blank:classify xs
classify (x:xs) = Comment:classify xs
unclassify :: Classified -> String
unclassify (Program s) = s
unclassify (Pre s) = '#':s
unclassify (Include i f) = '#':' ':show i ++ ' ':f
unclassify Blank = ""
unclassify Comment = ""
unlit :: String -> String -> String
unlit file lhs = (unlines
. map unclassify
. adjecent file (0::Int) Blank
. classify) (inlines lhs)
adjecent :: String -> Int -> Classified -> [Classified] -> [Classified]
adjecent file 0 _ (x :xs) = x : adjecent file 1 x xs -- force
evaluation of line number
adjecent file n y@(Program _) ([EMAIL PROTECTED] :xs) = error (message file n
"program" "comment")
adjecent file n y@(Program _) (x@(Include i f):xs) = x: adjecent f i y xs
adjecent file n y@(Program _) (x@(Pre _) :xs) = x: adjecent file (n+1) y xs
adjecent file n [EMAIL PROTECTED] (x@(Program _) :xs) = error (message file n
"comment" "program")
adjecent file n [EMAIL PROTECTED] (x@(Include i f):xs) = x: adjecent f i y
xs
adjecent file n [EMAIL PROTECTED] (x@(Pre _) :xs) = x: adjecent file (n+1) y
xs
adjecent file n [EMAIL PROTECTED] (x@(Include i f):xs) = x: adjecent f i
y xs
adjecent file n [EMAIL PROTECTED] (x@(Pre _) :xs) = x: adjecent file (n+1)
y xs
adjecent file n _ ([EMAIL PROTECTED] :xs) = x: adjecent file (n+1)
x xs
adjecent file n _ [] = []
message "\"\"" n p c = "Line "++show n++": "++p++ " line before "++c++" line.\n"
message [] n p c = "Line "++show n++": "++p++ " line before "++c++" line.\n"
message file n p c = "In file " ++ file ++ " at line "++show n++": "++p++ " line
before "++c++" line.\n"
-- Re-implementation of 'lines', for better efficiency (but decreased laziness).
-- Also, importantly, accepts non-standard DOS and Mac line ending characters.
inlines s = lines' s id
where
lines' [] acc = [acc []]
lines' ('\^M':'\n':s) acc = acc [] : lines' s id -- DOS
lines' ('\^M':s) acc = acc [] : lines' s id -- MacOS
lines' ('\n':s) acc = acc [] : lines' s id -- Unix
lines' (c:s) acc = lines' s (acc . (c:))
