Merge branch 'master' into working

[lambda.git] / code / ski_evaluator.hs

diff --git a/code/ski_evaluator.hs b/code/ski_evaluator.hs
index 845d6da..26f1c0e 100644 (file)
--- a/code/ski_evaluator.hs
+++ b/code/ski_evaluator.hs
@@ -1,13 +1,13 @@
-data Term = I | S | K | FA Term Term deriving (Eq, Show)      
+data Term = I | S | K | App Term Term deriving (Eq, Show)      
                                                               
-skomega = (FA (FA (FA S I) I) (FA (FA S I) I))                      
-test = (FA (FA K I) skomega)
+skomega = (App (App (App S I) I) (App (App S I) I))                      
+test = (App (App K I) skomega)
                                                               
 reduce_one_step :: Term -> Term                                      
 reduce_one_step t = case t of                                      
-  FA I a -> a                                                      
-  FA (FA K a) b -> a                                              
-  FA (FA (FA S a) b) c -> FA (FA a c) (FA b c)                      
+  App I a -> a                                                      
+  App (App K a) b -> a                                              
+  App (App (App S a) b) c -> App (App a c) (App b c)                      
   _ -> t                                                      
                                                               
 is_redex :: Term -> Bool                                      
@@ -18,7 +18,7 @@ reduce t = case t of
   I -> I                                                      
   K -> K                                                      
   S -> S                                                      
-  FA a b ->                                                       
-    let t' = FA (reduce a) (reduce b) in                      
+  App a b ->                                                       
+    let t' = App (reduce a) (reduce b) in                      
       if (is_redex t') then reduce (reduce_one_step t')      
                        else t'