Multiline strings and interpolation

Quasiquote 'str' implements multiline strings with interpolation. Interpolating a value into the string is done by $$ and interpolating anything with instance Show is $:$. Due to pretty deep limitations, the parser is not able to properly deduce associtivity of infix operators, so use lots and lots of parenthesis.

Repetitive patterns can be made with # symbol:

#<pattern> in <list>: <interpolated string> (|<interpolated string>)#

Where (|) denotes optional separator for the elements.

Multiline indentation is handled by aligning on smallest un-empty line after the first. Neither pattern matching nor nested #-patterns are supported, however, see example below.

Normal '\n' style escaping of special characters is intentionally not supported. Please use $endline$ or $"\n"$ style instead.

As an example, let's plot set of vectors with gnuplot:

 plotVecs :: [(String,[Double])] -> String
 plotVecs vs =  
     [$str| ## Plot multiple vectors
            plot #(n,_) in vs:'-' with lines lw 5 title $:n$ |, #
            #d in map snd vs:$singleVec d$$endline$e$endline$# |]
 where
  singleVec n = [$str|#(e,i) in zip n [1..]: $:i$ $:e$|$endline$#|]

*Gnuplotter> plotVecs [("A",[1..5]),("B",[2..6])]
# Plot multiple vectors
 plot '-' with lines lw 5 title "A" , '-' with lines lw 5 title "B" 
  1 1.0
  2 2.0
  3 3.0
  4 4.0
  5 5.0
 
 e
  1 2.0
  2 3.0
  3 4.0
  4 5.0
  5 6.0
 
 e

Change log

• 0.2.5.1 - Compiles with GHC 7.0.1
• 0.2.5.2 - Compiles with GHC 6.12