works except untyped trees and lists out of the box

diff --git a/a1/mart/skeleton1.icl b/a1/mart/skeleton1.icl
index dd17d73..128974d 100644 (file)
--- a/a1/mart/skeleton1.icl
+++ b/a1/mart/skeleton1.icl
@@ -105,8 +105,27 @@ listToGen [x:xs] = RIGHT (PAIR x xs)
 \r
 //2.3.         EITHER (PAIR 1 (PAIR 2 3)) UNIT \r
 //     Nope, it will leave the xs to be so it will be: EITHER (PAIR 1 [2,3])\r
-//2.4. Nope, not possible since they are basic types and they can't be\r
-//     converted to UNIT, EITHER or PAIR.\r
+//2.4. Yes, for Int and Char it works fine but for list and tuples you'll run\r
+//     into problems.\r
+//class toGen a :: a -> GenG a\r
+//\r
+//:: IntG :== EITHER UNIT (PAIR UNIT Int)\r
+//:: CharG :== EITHER UNIT (PAIR UNIT Char)\r
+//:: ListG a :== EITHER UNIT (PAIR a [a])\r
+//:: GenG a :== EITHER IntG (EITHER CharG (ListG a))\r
+//\r
+//instance toGen Int where\r
+//     toGen 0 = LEFT (LEFT UNIT)\r
+//     toGen x = LEFT (RIGHT (PAIR UNIT (x-1)))\r
+//\r
+//instance toGen Char where\r
+//     toGen x\r
+//     | fromChar x == 0 = RIGHT (LEFT (LEFT UNIT))\r
+//     | otherwise = RIGHT (LEFT (RIGHT (PAIR UNIT (x-(toChar 1)))))\r
+//\r
+//instance toGen [] where\r
+//     toGen [] = RIGHT (RIGHT (LEFT UNIT))\r
+//     toGen [x:xs] = RIGHT (RIGHT (RIGHT (PAIR (x xs))))\r
 \r
 //3. Ordering via generic representation\r
 //3.1\r
@@ -151,5 +170,10 @@ treeToGen (Bin x xr xl) = RIGHT (PAIR x (PAIR xr xl))
 \r
 Start = [Red >< Yellow, Blue >< Yellow, Blue >< Blue,\r
        (Bin 1 Tip Tip) >< Tip,\r
+       [1, 2] >< [2, 3],\r
+       [1, 2] >< [1, 2],\r
+       [1, 3] >< [1, 2],\r
+//     [] >< [],\r
+//     Tip >< Tip,\r
        (Bin 1 Tip Tip) >< (Bin 1 Tip Tip),\r
        Tip >< (Bin 1 Tip Tip) ]\r