diff --git a/Baggins.cabal b/Baggins.cabal
new file mode 100644
--- /dev/null
+++ b/Baggins.cabal
@@ -0,0 +1,25 @@
+-- Initial Manhattan.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                Baggins
+version:             1.0
+synopsis:            Tools for self-assembly
+-- description:         
+homepage:            http://pageperso.lif.univ-mrs.fr/~pierreetienne.meunier/Baggins
+license:             GPL-3
+license-file:        LICENSE
+author:              Pierre-Etienne Meunier
+maintainer:          pierre-etienne.meunier@lif.univ-mrs.fr
+-- copyright:           
+category:            Math
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+library
+  exposed-modules:     Math.SelfAssembly.Baggins
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.6 && <4.7,cairo,containers,mtl>=2
+  -- hs-source-dirs:      
+  default-language:    Haskell2010
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,675 @@
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+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
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+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
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+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+              END OF TERMS AND CONDITIONS
+
+     How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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+
+Also add information on how to contact you by electronic and paper mail.
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+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+
diff --git a/Math/SelfAssembly/Baggins.hs b/Math/SelfAssembly/Baggins.hs
new file mode 100644
--- /dev/null
+++ b/Math/SelfAssembly/Baggins.hs
@@ -0,0 +1,611 @@
+{-#LANGUAGE BangPatterns #-}
+module Math.SelfAssembly.Baggins (
+  Tile,Program,runProgram,execProgram,simulate,
+  -- * Initialization
+  seed,
+  -- * Basic moves
+  movex,movey,discreteVect,
+  -- * Combinators
+  repete,pump,
+  -- * Rembering specific tile types - equivalents to formal "let".
+  Cur(..),currentTile,nextTile,prevTile,
+  -- * Editing and branching - equivalents to the formal "bind" and "from".
+  Dir(..),bind,rewindBy,rewindTo,eraseAfter,
+  -- * Coloring tiles - tile decorations
+  Color,setColor,red,green,blue,black,
+  -- * Debugging and output
+  plot,PlotOptions(..),defaultPlot,
+  traceTile,tikzPlot
+  ) where
+
+import Control.Monad.State
+import qualified Data.Map as M
+import qualified Data.IntMap as IM
+import qualified Data.IntSet as S
+import Graphics.Rendering.Cairo hiding(scale)
+import Foreign.Storable
+import Data.Bits(shiftL,shiftR,(.&.),(.|.))
+import System.IO
+import Numeric
+import Debug.Trace
+
+-- | The tile datatype
+data Tile=Tile {n::Int, s::Int, o::Int, e::Int,color::(Double,Double,Double)} deriving (Eq,Show)
+
+sortTile::M.Map Int Tile -> (M.Map Int [Int], M.Map Int [Int], M.Map Int [Int], M.Map Int [Int])
+sortTile t=
+  M.foldlWithKey' (\(mn,ms,mo,me) k a->
+                    let { addm f m=
+                             case M.lookup (f a) m of {
+                               Nothing->M.insert (f a) [k] m;
+                               Just x->M.insert (f a) (k:x) m
+                               }
+                        }
+                    in
+                     (addm n mn,addm s ms,addm o mo,addm e me)
+                  )
+  (M.empty,M.empty,M.empty,M.empty) t
+
+
+type Position=(Int,Int)
+coup x y=(x,y)--(x`shiftL`(intlen*4)) .|. y;
+uncoup p=p -- (p`shiftR`(intlen*4), p .&. ((1`shiftL`(intlen*4) - 1)));
+incrx p=let (x,y)=uncoup p in coup (x+1) y
+incry p=let (x,y)=uncoup p in coup x (y+1)
+decrx p=let (x,y)=uncoup p in coup (x-1) y
+decry p=let (x,y)=uncoup p in coup x (y-1)
+
+
+posLookup=M.lookup
+posInsert=M.insert
+posFindWithDefault=M.findWithDefault
+posFromList=M.fromList
+posFoldlWithKey'=M.foldlWithKey'
+
+-- | @simulate file margin w h showGlues seeds tiles@ simulates the given
+-- tileset, with seeds at the given positions @(x,y,type)@, and
+-- returns the maximal manhattan distance reached. The @showGlues@
+-- argument indicates whether glues should be written in the output
+-- file (results in bigger files).
+simulate::Int->Int->[(Int,Int,Int)]->[(Int,Int)]->M.Map Int Tile->
+          IO (Int,Int,Int,Int,M.Map Position Int)
+simulate nw nh seeds blockers tiles_=do {
+  let { (nn,ss,oo,ee)=sortTile tiles_;
+        intlen=sizeOf (0::Int);
+        coup x y=(x,y);--(x`shiftL`(intlen*4)) .|. y;
+        uncoup p=p; -- (p`shiftR`(intlen*4), p .&. ((1`shiftL`(intlen*4) - 1)));
+        incrx p=let (x,y)=uncoup p in coup (x+1) y;
+        incry p=let (x,y)=uncoup p in coup x (y+1);
+        decrx p=let (x,y)=uncoup p in coup (x-1) y;
+        decry p=let (x,y)=uncoup p in coup x (y-1);
+      };
+  -- grid : positions remplies, p: position à considérer pour placer une tuile
+  let { simu !x0 !y0 !x1 !y1 grid []=return (x0,y0,x1,y1,grid);
+        simu !x0 !y0 !x1 !y1 grid (p:tl)=
+          if any (==p) blockers then simu x0 y0 x1 y1 grid tl else do {
+          let { (x,y)=uncoup p };
+          case posLookup p grid>>=(\t->M.lookup t tiles_)  of {
+            Nothing->simu (min x x0) (min y y0) (max x x1) (max y y1) grid tl;
+            Just tt->do {
+              let { deterministe l@(_:_:_)=
+                       putStrLn $ "Non-deterministic choice at position "++show (x,y)++": "
+                       ++show (map (\u->M.lookup u tiles_) l);
+                    deterministe _=return () };
+              (nt,gr0)<-if y>=(nh-1) then return ([],grid) else do {
+                let { pos=case posLookup (incry p) grid of {
+                         Nothing->posFindWithDefault [] (n tt) ss;
+                         _->[]
+                         }
+                    };
+                deterministe pos;
+                case pos of {
+                  []->return ([],grid);
+                  (hh:_)->return ([(incry p)], posInsert (incry p) hh grid)
+                  }
+                };
+              (st,gr1)<-if y<1 then return (nt,gr0) else do {
+                let { pos=case posLookup (decry p) gr0 of {
+                         Nothing->posFindWithDefault [] (s tt) nn;
+                         _->[]
+                         }
+                    };
+                deterministe pos;
+                case pos of {
+                  []->return (nt,gr0);
+                  (hh:_)->return ((decry p):nt, posInsert (decry p) hh gr0)
+                  }
+                };
+              (et,gr2)<-if x>=(nw-1) then return (st,gr1) else do {
+                let { pos=case posLookup (incrx p) gr1 of {
+                         Nothing->posFindWithDefault [] (e tt) oo;
+                         _->[]
+                         }
+                    };
+                deterministe pos;
+                case pos of {
+                  []->return (st,gr1);
+                  (hh:_)->return ((incrx p):st, posInsert (incrx p) hh gr1)
+                  }
+                };
+              (ot,gr3)<-if x<1 then return (et,gr2) else do {
+                let { pos=case posLookup (decrx p) gr2 of {
+                         Nothing->posFindWithDefault [] (o tt) ee;
+                         _->[]
+                         }
+                    };
+                deterministe pos;
+                case pos of {
+                  []->return (et,gr2);
+                  (hh:_)->return ((decrx p):et, posInsert (decrx p) hh gr2)
+                  }
+                };
+              simu (min x0 x) (min y0 y) (max x1 x) (max y1 y) gr3 $!
+              tl++reverse ot
+              };
+            };
+          }
+      };
+  simu nw nh 0 0 (posFromList [(coup a b,c)|(a,b,c)<-seeds]) [coup a b | (a,b,_)<-seeds];
+  }
+
+data PlotOptions=Plot { showGlues::Bool, showPaths::Bool, offset::Double, scale::Double, font::String, fontSize::Double }
+defaultPlot=Plot { showGlues=True,offset=100,showPaths=False,scale=0.1, font="Arial",fontSize=0.18 }
+
+plot::FilePath->PlotOptions->M.Map Int Tile->M.Map Position Int->IO()
+plot file opts tiles_ grid=do {
+  let { scal=scale opts;
+        off=offset opts;
+        (nw,nh)=M.foldlWithKey (\(x,y) (x',y') _->(max x x',max y y')) (0,0) grid;
+        (w0,h0)=M.foldlWithKey (\(x,y) (x',y') _->(min x x',min y y')) (nw,nh) grid;
+        h=(fromIntegral $ nh-h0+1)*scal+2*off;
+        w=(fromIntegral $ nw-w0+1)*scal+2*off };
+  withPDFSurface file w h $ \surface->renderWith surface $ do {
+    translate (-fromIntegral w0*scal) (fromIntegral h0*scal);
+    selectFontFace (font opts) FontSlantNormal FontWeightNormal;
+    setFontSize $ fontSize opts*scal;
+    let { drawPicture pos tt tset=do {
+             let { (x,y)=uncoup pos };
+             case M.lookup tt tiles_ of {
+               Nothing->return ();
+               Just t->do {
+                 let {(a,b,c)=color t} in
+                 {-
+                 let {hue=(fromIntegral $ M.findIndex tt tiles_) / (fromIntegral $ M.size tiles_);
+                      sat=0.9;
+                      val=0.8;
+                      col=hsv (360*hue) sat val;
+                      a=channelRed col;b=channelGreen col;c=channelBlue col };
+-}
+                 setSourceRGB a b c;
+                 rectangle (off+scal*fromIntegral x)
+                 (h-off-scal - scal*fromIntegral y)
+                 scal scal;
+                 closePath;
+                 setLineWidth 0.01;
+                 stroke;
+                 if showGlues opts then do {
+                   let {glueN=if n t<0 then "" else show $ n t;
+                        glueS=if s t<0 then "" else show $ s t;
+                        glueE=if e t<0 then "" else show $ e t;
+                        glueO=if o t<0 then "" else show $ o t};
+                   ten<-textExtents glueN;
+                   tes<-textExtents glueS;
+                   tee<-textExtents glueE;
+                   teo<-textExtents glueO;
+                   if showPaths opts then do {
+                     setLineWidth 1;
+                     if (n t>=0 && s t>=0) || (e t>=0 && o t>=0) then do {
+                       (toN,toS)<-
+                          if n t>=0 && s t>=0 then do {
+                            moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(fromIntegral y));
+                            lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1+fromIntegral y));
+                            return (False,False);
+                            } else return (n t>=0,s t>=0);
+                       (toE,toO)<-if e t>=0 && o t>=0 then do {
+                         moveTo (off+scal*(fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         lineTo (off+scal*(1+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         return (False,False)
+                         } else return (e t>=0, o t>=0);
+                       if toN then do {
+                         moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1+fromIntegral y));
+                         } else return ();
+                       if toS then do {
+                         moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(fromIntegral y));
+                         } else return ();
+                       if toE then do {
+                         moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         lineTo (off+scal*(1+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         } else return ();
+                       if toO then do {
+                         moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         lineTo (off+scal*(fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                         } else return ();
+                       } else do {
+                       if s t>=0 then
+                         moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(fromIntegral y))
+                       else
+                         if n t>=0 then
+                           moveTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1+fromIntegral y))
+                         else
+                           if e t>=0 then
+                             moveTo (off+scal*(1+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y))
+                           else
+                             if o t>=0 then
+                               moveTo (off+scal*(fromIntegral x)) (h-off-scal*(1/2+fromIntegral y))
+                             else
+                               return (); -- n'arrive jamais
+                       lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y));
+                       if e t>=0 then
+                         lineTo (off+scal*(1+fromIntegral x)) (h-off-scal*(1/2+fromIntegral y))
+                       else
+                         if o t>=0 then
+                           lineTo (off+scal*(fromIntegral x)) (h-off-scal*(1/2+fromIntegral y))
+                         else
+                           if n t>=0 then
+                             lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(1+fromIntegral y))
+                           else
+                             if s t>=0 then
+                               lineTo (off+scal*(1/2+fromIntegral x)) (h-off-scal*(fromIntegral y))
+                             else
+                               return (); -- n'arrive jamais
+                       };
+                       stroke;
+                     setLineWidth 0.01;
+                   } else return ();
+                   moveTo (off+scal*(1/2+fromIntegral x)-textExtentsWidth ten/2)
+                   (h-off-scal-scal*fromIntegral y+textExtentsHeight ten+0.1*scal);
+                   showText glueN;
+
+                   let { yoff=textExtentsYbearing tes+textExtentsHeight tes };
+                   moveTo (off+scal*(1/2+fromIntegral x)-textExtentsWidth tes/2)
+                   (h-off-scal-scal*(fromIntegral y-1) - yoff-0.1*scal);
+                   showText glueS;
+
+                   save;
+                   --
+                   moveTo (off+scal*(fromIntegral x)) (h-off-scal-scal*(fromIntegral y-1/2));
+                   rotate $ -pi/2;
+                   (cx,cy)<-getCurrentPoint;
+                   moveTo (cx-textExtentsWidth teo/2) (cy+textExtentsHeight teo+0.1*scal);
+                   showText glueO;
+                   --
+                   moveTo (cx-textExtentsWidth tee/2) (cy+scal-0.1*scal);
+                   showText glueE;
+                   --
+                   restore;
+                   } else return ()
+                 };
+               };
+             return $ if tt>=0 then S.insert tt tset else tset
+             }
+        };
+    tset<-posFoldlWithKey' (\m k a->do {
+                              m_<-m;
+                              drawPicture k a m_
+                              }) (return S.empty) grid;
+    if S.size tset < M.size tiles_ then
+      liftIO $ putStrLn $ "Warning: only "++show (S.size tset)++" out of "++
+      show (M.size tiles_)++" tiles used"
+    else return ();
+    };
+  }
+
+defaultTile::Tile
+defaultTile=Tile { n= -1,s= -2, o= -1, e= -2, color=(0,0,0) }
+
+-- lastGlue est la dernière glue utilisée
+data St=State { lastGlue::Int, tiles::M.Map Int Tile, lastTile::Maybe Int, curColor::Color,
+                seeds::[(Int,Int,Int)] }
+       --deriving Show
+empty::St
+empty=State { lastGlue=0,tiles=M.empty,lastTile=Nothing, curColor=black,seeds=[] }
+type Program=State St
+
+
+-- | Adds a new seed to the program, at the given position. There may
+-- be several seeds, and they will all be placed before anything else
+-- is grown.
+seed::Int->Int->Program ()
+seed x y=do
+  st<-get
+  let s=if M.null $ tiles st then 0 else (1+(fst $ M.findMax $ tiles st))
+  put $ st { seeds=(x,y,s):seeds st,
+             lastTile=Just s,
+             tiles=M.insert s defaultTile $ tiles st }
+
+move_::Bool->Int->Program ()
+move_ vertical m=do
+  st<-get
+  let (lg,tiles0,connected)=case lastTile st of {
+        Nothing->(lastGlue st,tiles st,False);
+        Just x->case M.lookup x $ tiles st of {
+          Nothing->(lastGlue st,tiles st,False);
+          Just y->
+            if vertical then
+              if m>=0 then
+                (if n y<0 then lastGlue st+1 else n y,
+                 M.insert x (y { n=if n y<0 then lastGlue st+1 else n y }) $ tiles st,
+                 True)
+              else
+                (if s y<0 then lastGlue st+1 else s y,
+                 M.insert x (y { s=if s y<0 then lastGlue st+1 else s y }) $ tiles st,
+                 True)
+            else
+              if m>=0 then
+                (if e y<0 then lastGlue st+1 else e y,
+                M.insert x (y { e=if e y<0 then lastGlue st+1 else e y }) $ tiles st,
+                True)
+              else
+                (if o y<0 then lastGlue st+1 else o y,
+                 M.insert x (y { o=if o y<0 then lastGlue st+1 else o y }) $ tiles st,
+                 True)
+          }
+        }
+      t=if vertical then
+          if m>=0 then
+            [ defaultTile { n=if i==(lg+m-1) then (-1) else i+1,
+                            s=if i==lg && not connected then (-2) else i,
+                            color=curColor st } | i<-[lg..(lg+m-1)] ]
+          else
+            [ defaultTile { s=if i==(lg-m-1) then (-2) else i+1,
+                            n=if i==lg && not connected then (-1) else i,
+                            color=curColor st } | i<-[lg..(lg-m-1)] ]
+        else
+          if m>=0 then
+            [ defaultTile { e=if i==(lg+m-1) then (-2) else i+1,
+                            o=if i==lg && not connected then (-1) else i,
+                            color=curColor st } | i<-[lg..(lg+m-1)] ]
+          else
+            [ defaultTile { o=if i==(lg-m-1) then (-1) else i+1,
+                            e=if i==lg && not connected then (-2) else i,
+                            color=curColor st } | i<-[lg..(lg-m-1)] ]
+      nextTiles=foldl (\ts x->M.insert (if M.null ts then 0 else (1+fst (M.findMax ts))) x ts)
+                tiles0 t
+
+  put $ st { lastGlue=lg+abs m-1,
+             lastTile=if M.null nextTiles then Nothing else (Just $ fst $ M.findMax nextTiles),
+             tiles=nextTiles }
+
+-- | Move by 1 tile along the y-axis
+movey::Int->Program ()
+movey=move_ True
+
+-- | Move by 1 tile along the x-axis
+movex::Int->Program ()
+movex=move_ False
+
+repeat_::Int->Program ()->Program ()
+repeat_ k m=if k<=0 then return () else do
+  m
+  repeat_ (k-1) m
+
+-- | Repeat a program a given number of times. If the original program
+-- produces @n@ tile types, then repeating it @t@ times produces @mt@
+-- tile types.
+repete::Int->Program ()->Program ()
+repete a b=do {
+  st0<-get;
+  repeat_ a b;
+  st1<-get;
+  put $ st1 { curColor=curColor st0 }
+}
+
+-- | Approximates a discrete vector, by walking as close as possible
+-- to the corresponding straight line.
+discreteVect::Int->Int->Program ()
+discreteVect x0 y0=
+  let disc x y=
+        if x0==x then movey (y0-y) else
+          if y0==y then movex (x0-x) else
+            let xf=(fromIntegral x0/fromIntegral y0)*(fromIntegral y)
+                xx0=(fromIntegral x0/fromIntegral y0)*(fromIntegral (y+1))::Double
+            in
+             if (abs $ xf-fromIntegral (x+1)) <= (abs $ fromIntegral x-xx0) then
+              if x0>x then do { movex 1; disc (x+1) y }
+              else do { movex (-1); disc (x-1) y }
+            else
+              if y0>y then do { movey 1; disc x (y+1) }
+              else do { movey (-1); disc x (y-1) }
+  in
+   disc 0 0
+
+-- | Pump a given program, that is, allowing its first tile to attach
+-- to its last tile. It is up to the user to check that this is
+-- possible; the assembly is likely to stop else.
+pump::Program ()->Program ()
+pump m=do
+  -- À priori, assembler m deux fois devrait suffire.  Mais il y a un
+  -- cas particulier bizarre quand on commence à pomper dès la
+  -- première tuile du programme, et on doit l'assembler trois fois,
+  -- puis conserver l'assemblage du milieu.
+  st0<-get
+  m
+  st1<-get
+  put $ st1 { lastGlue=lastGlue st0 }
+  m
+  st2<-get
+  put $ st2 { lastGlue=lastGlue st0 }
+  m
+  st3<-get
+  let { (max0,_)=M.findMax $ tiles st0;
+        (max1,_)=M.findMax $ tiles st1;
+        (max2,_)=M.findMax $ tiles st2;
+        (m0,_)=M.split (max0+1) $ tiles st3;
+        (_,m1)=M.split max1 $ tiles st3;
+        (m2,_)=M.split (max2+1) m1;
+        t=M.foldlWithKey' (\m3 k a->M.insert (k-max1+max0) a m3) m0 m2
+      }
+  put $ st3 { tiles=t,curColor=curColor st0,lastTile=Just $ fst $ M.findMax t }
+
+
+-- | Tile colors
+type Color=(Double,Double,Double)
+
+red,green,blue,black::Color
+red=(1,0,0)
+green=(0,1,0)
+blue=(0,0,1)
+black=(0,0,0)
+
+-- | Set the current color
+setColor::Color->Program ()
+setColor col=do
+  st<-get
+  put $ st { curColor=col }
+
+
+newtype Cur=Cur Int
+
+-- | Get the last tile placed (raises error if no tile has been placed).
+currentTile::Program Cur
+currentTile=do
+  st<-get
+  case lastTile st of
+    Nothing->error "currentTile not defined"
+    Just x->return $ Cur x
+
+-- | Get the tile immediately following a given tile in program order.
+nextTile::Cur->Program Cur
+nextTile (Cur a)=do
+  st<-get
+  let (_,v)=M.split a $ tiles st
+  if M.null v then error "no next tile defined" else return $ Cur $ fst $ M.findMin v
+
+-- | Get the tile immediately following a given tile in program order.
+prevTile::Cur->Program Cur
+prevTile (Cur a)=do
+  st<-get
+  let (u,_)=M.split a $ tiles st
+  if M.null u then error "no previous tile defined" else return $ Cur $ fst $ M.findMax u
+
+
+-- | Go back to a specific tile.
+rewindTo::Cur->Program ()
+rewindTo (Cur t)=do
+  st<-get
+  put $ st { lastTile=Just t }
+
+-- | Go back by the given amount of tile types.
+rewindBy::Int->Program ()
+rewindBy n0=if n0<0 then error "rewind by negative amount" else do
+  st<-get
+  if M.null $ tiles st then error "rewind on empty tileset" else do
+    let { del i m k=
+             if i<0 then k else
+               let { ((a,_),m')=M.deleteFindMax m } in
+               del (i-1) m' a;
+          m0=case lastTile st of { Nothing->tiles st;
+                                  Just a->fst $ M.partitionWithKey (\k _->k<=a) $ tiles st }
+        }
+    put $ st { lastTile=Just $ del n0 m0 0 }
+
+
+-- | Directions, or sides of tiles
+data Dir=N | S | O | E
+
+-- | Binds the given tile to the given side of the current tile. This
+-- function modifies the given tile if and only if the complementary
+-- side was not used. This modification can result in unwanted
+-- assemblies.
+bind::Dir->Cur->Program ()
+bind d (Cur t)=do
+  st<-get
+  case lastTile st of
+    Nothing->return ()
+    Just a->
+      case (M.lookup a $ tiles st, M.lookup t $ tiles st) of
+        (Just b, Just tt)->
+          let (nextTiles,nextGlue)=case d of
+                N->if s tt<0 then
+                     (M.insert t (tt { s=lastGlue st+1 }) $
+                      M.insert a (b { n=lastGlue st+1 }) $ tiles st,
+                      lastGlue st+1)
+                   else
+                     (M.insert a (b { n=s tt }) $ tiles st,lastGlue st)
+                S->if n tt<0 then
+                     (M.insert t (tt { n=lastGlue st+1 }) $
+                      M.insert a (b { s=lastGlue st+1 }) $ tiles st,
+                      lastGlue st+1)
+                   else
+                     (M.insert a (b { s=n tt }) $ tiles st,lastGlue st)
+                O->if e tt<0 then
+                     (M.insert t (tt { e=lastGlue st+1 }) $
+                      M.insert a (b { o=lastGlue st+1 }) $ tiles st,
+                      lastGlue st+1)
+                   else
+                     (M.insert a (b { o=e tt }) $ tiles st,lastGlue st)
+                E->if o tt<0 then
+                     (M.insert t (tt { o=lastGlue st+1 }) $
+                      M.insert a (b { e=lastGlue st+1 }) $ tiles st,
+                      lastGlue st+1)
+                   else
+                     (M.insert a (b { e=o tt }) $ tiles st,lastGlue st)
+          in
+           put $ st { tiles=nextTiles, lastGlue=nextGlue }
+        _->return ()
+
+-- | Delete every tile produced after the given tile. Mostly useful in
+-- combination with 'currentTile'.
+eraseAfter::Cur->Program ()
+eraseAfter (Cur a)=do
+  st<-get
+  put $ st { tiles=fst $ M.split (a+1) $ tiles st }
+
+-- | Run the program, returning its return value, along with the produced tileset.
+runProgram::Program a->(a,[(Int,Int,Int)],M.Map Int Tile)
+runProgram p=
+  let (a,b)=runState p empty in
+  (a,seeds b,tiles b)
+
+-- | Run the program, returning the produced tileset.
+execProgram::Program ()->([(Int,Int,Int)],M.Map Int Tile)
+execProgram p=
+  let st=execState p empty in (seeds st,tiles st)
+
+
+traceTile (Cur t)=do
+  st<-get
+  traceShow (M.lookup t $ tiles st) $ return ()
+
+
+tikzTile::Tile->Double->Double->Double->String
+tikzTile t sc x y=
+  "\\draw"++show (sc*x,sc*y)++"rectangle"++(show $ (sc*(x+1),sc*(y+1)))++";"++
+  (if o t>=0 then
+     "\\draw"++show (sc*x,sc*(y+0.5))++"node[anchor=west]{"++(show $ o t)++"};"
+   else "")++
+  (if n t>=0 then
+     "\\draw"++show (sc*(x+0.5),sc*(y+1))++"node[anchor=north]{"++(show $ n t)++"};"
+   else "")++
+  (if e t>=0 then
+     "\\draw"++show (sc*(x+1),sc*(y+0.5))++"node[anchor=east]{"++(show $ e t)++"};"
+   else "")++
+  (if s t>=0 then
+     "\\draw"++show (sc*(x+0.5),sc*y)++"node[anchor=south]{"++(show $ s t)++"};"
+   else "")
+
+
+tikzPlot::FilePath->PlotOptions->M.Map Int Tile->M.Map Position Int->IO()
+tikzPlot file opts tiles_ grid=
+  withFile file WriteMode $ \h->do {
+    let { s=scale opts / (10/fontSize opts);
+          s0=scale opts;
+          (x0,y0,x1,y1)=M.foldlWithKey (\(a,b,c,d) (x,y) _->(min a x,min b y,max c x,max d y)) (maxBound,maxBound,minBound,minBound) grid;
+          showf (x,y)="("++showFFloat (Just 4) x (","++showFFloat (Just 4) y ")")
+          };
+    --hPutStr h "\\begin{tikzpicture}";
+    hPutStr h $ "\\draw[use as bounding box,draw=none,fill=none]";
+    hPutStr h $ showf (fromIntegral x0*s0,fromIntegral y0*s0);
+    hPutStr h $ "rectangle";
+    hPutStr h $ showf (fromIntegral (x1+1)*s0,fromIntegral (y1+1)*s0);
+    hPutStr h $ ";\\begin{scope}[transform canvas={scale="++show (1*s)++"}]";
+    mapM_ (\((x,y),t)->
+            case M.lookup t tiles_ of {
+              Just tt->hPutStr h $ tikzTile tt (10/fontSize opts) (fromIntegral x) (fromIntegral y);
+              Nothing->return ()
+              }) $ M.toList grid;
+    hPutStrLn h $ "\\end{scope}";
+    --hPutStrLn h $ "\\end{tikzpicture}"
+    }
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain