started a subdir for the book

1 files changed, 21 insertions, 0 deletions

diff --git a/book/examples/chapter8/Logic.gf b/book/examples/chapter8/Logic.gf
new file mode 100644
index 000000000..f2b292428
--- /dev/null
+++ b/book/examples/chapter8/Logic.gf
@@ -0,0 +1,21 @@
+abstract Logic = {
+flags startcat = Stm ;
+cat
+  Stm ;        -- top-level statement 
+  Prop ;       -- proposition 
+  Atom ;       -- atomic formula
+  Ind ;        -- individual term 
+  Dom ;        -- domain expression
+  Var ;        -- variable
+  [Prop] {2} ; -- list of propositions, 2 or more
+  [Var] {1} ;  -- list of variables, 1 or more
+fun
+  SProp : Prop -> Stm ;
+  And, Or : [Prop] -> Prop ;
+  If  : Prop -> Prop -> Prop ;
+  Not : Prop -> Prop ;
+  PAtom : Atom -> Prop ;
+  All, Exist : [Var] -> Dom -> Prop -> Prop ;
+  IVar : Var -> Ind ;
+  VString : String -> Var ;
+}