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+This library implements a simple eDSL for linear programming and a simple
+wrapper around lp_solve (potentially other solvers can also be plugged in
+easily).  Here's how to solve the farmer example from the lp_solve
+documentation:
+
+> Suppose a farmer has 75 acres on which to plant two crops: wheat and barley.
+> To produce these crops, it costs the farmer (for seed, fertilizer, etc.) $120
+> per acre for the wheat and  $210 per acre for the barley. The farmer has
+> $15000 available for expenses. But after the harvest, the farmer must store
+> the crops while awaiting favourable market conditions. The farmer has storage
+> space for 4000 bushels. Each acre yields an average of 110 bushels of wheat
+> or 30 bushels of barley.  If the net profit per bushel of wheat (after all
+> expenses have been subtracted) is $1.30 and for barley is $2.00, how should
+> the farmer plant the 75 acres to maximize profit?
+
+    import Control.Monad
+    import Math.LinProg.LPSolve
+    import Math.LinProg.Types
+
+    data Crop = Wheat | Barley
+      deriving (Eq, Show, Ord)
+
+    lp :: LinProg Double Crop ()
+    lp = do
+      let vs@[w, b] = map var [Wheat, Barley]
+      obj $ negate $ 110 * 1.3 * w + 30 * 2 * b
+      120 * w + 210 * b <: 15000
+      110 * w + 30 * b <: 4000
+      w + b <: 75
+
+    main :: IO ()
+    main = do
+      sol <- solve lp
+      print sol
+
+This outputs the solution: Right [(Wheat,21.875),(Barley,53.12499999999999)].
+Due to the monadic structure one can build up LPs using the usual monadic
+controls such as mapM/forM etc, making it quite easy to specify constraints.