||names defined in this file are not in scope for users - they are part
||of the internal mechanisms of the Miranda system.

||the following three identifiers are "untypeable" and defined internally
||changetype::*->**  ||primitive function, semantically equivalent to id
||first::*->**	||gets first element of a tuple
||rest::*->**	||gets rest of a tuple (i.e. without first component)

||offside::[char] ||defined internally and used by indent, see below

  diagonalise :: [[*]]->[*]  ||used by [//] comprehensions
  diagonalise x = diag 1 x   ||when nested does "cantorian" diagonalisation
  diag n [] = []
  diag n x = map hd px++diag (#px+1)rest, otherwise
	     where
	     px = filter (~=[]) (take n x)
	     rest = map tl px ++ drop n x
  listdiff::[*]->[*]->[*] ||listdiff defines the action of "--"
  listdiff x [] = x
  listdiff x (b:y) = listdiff (remove b x) y
  remove b [] = []
  remove b (a:x) = x, if a=b
                 = a:remove b x, otherwise
  showbool::bool->[char]
  showbool True = "True"
  showbool False = "False"
||shownum defined internally
  base r x = "0", if x=0 ||base is used by charname
           = f x, otherwise
             where
             f 0 = []
             f n = f(n div r) ++ [mkdigit(n mod r)]
  mkdigit n = decode(n + code '0'), if n<10
            = decode(n - 10 + code 'a'), if 10<=n<36
  showchar::char->[char]
  showchar x = "'" ++ charname x ++ "'"
||note - charname has the right conventions for showchar
||i.e. ' is escaped and " is not escaped - showstring inverts this
  charname '\\' = "\\\\"
  charname '\''  = "\\\'"
  charname x = [x], if 32 <= code x < 127 \/ 160 <= code x < 256
  charname '\a' = "\\a"
  charname '\b' = "\\b"
  charname '\f' = "\\f"
  charname '\n' = "\\n"
  charname '\r' = "\\r"
  charname '\t' = "\\t"
  charname '\v' = "\\v"
  charname x = "\\" ++ pad 3 (base 10 n),  if n<1000 ||H=this case only & no pad
             = "\\x" ++ pad 4 (base 16 n), if n<=0xffff
             = "\\X" ++ pad 6 (base 16 n), otherwise
               where
               n = code x
               pad w s = rep(w-#s)'0'++s
               rep n x = [],            if n<=0
                       = x:rep (n-1) x, otherwise
  showlist::(*->[char])->[*]->[char]
  showlist f x = '[':rest
		 where
		 rest = "]", if x=[]
		      = f(hd x)++foldr g "]" (tl x), otherwise
	         g a s = ',':f a++s
  showstring::[char]->[char]
  showstring x = '"' : showstr x
  showstr [] = "\""
  showstr ('"':x) = "\\\"" ++ showstr x
  showstr (a:x) = s ++ showstr x ||for Haskell style padding use s1 here
                  where          ||see also line marked H above
                  s = charname a
||                s1 = s ++ "\\&", if clash s x
||                   = s, otherwise
||                clash ('\\':c:cs) (d:ds) = digit c & digit d
||                clash s x = False
  digit c = '0' <= c <= '9'
  shownum1::num->[char]
  shownum1 n = "("++shownum n++")", if n<0
	     = shownum n, otherwise
  showparen::(*->[char])->*->[char]
  showparen f x = "("++f x++")"
  showpair::(*->[char])->(**->[char])->***->[char]
  showpair f1 f2 tup = f1(first tup)++","++f2(rest tup)
  showvoid::()->[char]
  showvoid () = "()"
  showfunction::(*->**)->[char]
  showfunction x = "<function>"
  showabstract::*->[char]
  showabstract x = "<abstract ob>"
  showwhat::*->[char]
  showwhat x = error "undeclared show-function", if x=x
||the following function is used to implement the offside rule (under %bnf)
  indent :: *->**->** || * is type of `col' function, ** is parser
  outdent :: *->*     || * is a parser
  indent = changetype indent1
  outdent = changetype outdent1
  indent1 col f ((a,s):x) 
    = f ((a,s):cutoff col (col s) x), if a~=offside
  indent1 col f x = f x
  cutoff col n = g
  	         where
  	         g ((a,s):x) = (a,s):g x, if col s>=n
                             = (offside,s):(a,s):x, otherwise
                 g [] = []
  outdent1 f = reconstruct.f
  reconstruct (m:x) = m:g x
                      where
  		      g ((a,s):x) = x, if a=offside
                      g (t:x) = t:g x
  		      g [] = []
  reconstruct fail = fail  ||internal repn of failure is a non-CONS object
||offside is defined internally and differs from every string