Add example scripts

README.md

@@ -89,7 +89,7 @@ cargo run -- repl
 cargo run -- gui
 
 # Run a script file
-cargo run -- script examples/session.chase
+cargo run -- script examples/scripts/ancestor.chase
 ```
 
 The REPL and GUI share a minimal command language:

examples/scripts/README.md

@@ -0,0 +1,13 @@
+# Example Scripts
+
+These scripts can be executed with:
+
+```bash
+make script SCRIPT=examples/scripts/ancestor.chase
+```
+
+Available examples:
+
+- `ancestor.chase`: transitive closure over `Parent/2`
+- `employee_departments.chase`: existential rule that creates labeled nulls
+- `same_team.chase`: conjunctive query with a self-join

examples/scripts/ancestor.chase

@@ -0,0 +1,11 @@
+# Derive ancestors from parent relationships.
+
+fact Parent(alice, bob).
+fact Parent(bob, carol).
+fact Parent(carol, dave).
+
+rule Parent(?X, ?Y) -> Ancestor(?X, ?Y).
+rule Ancestor(?X, ?Y), Parent(?Y, ?Z) -> Ancestor(?X, ?Z).
+
+run.
+query Ancestor(?X, ?Y)?

examples/scripts/employee_departments.chase

@@ -0,0 +1,11 @@
+# Existential rule example: each employee works in some department.
+
+fact Employee(alice).
+fact Employee(bob).
+fact Employee(carol).
+
+rule Employee(?X) -> WorksIn(?X, ?Dept).
+
+run.
+show facts
+query WorksIn(?X, ?Dept)?

examples/scripts/same_team.chase

@@ -0,0 +1,11 @@
+# Query people who share a manager.
+
+fact ManagedBy(alice, eve).
+fact ManagedBy(bob, eve).
+fact ManagedBy(carol, frank).
+
+rule ManagedBy(?X, ?M), ManagedBy(?Y, ?M) -> SameTeam(?X, ?Y).
+
+run.
+query SameTeam(?X, ?Y)?
+query SameTeam(alice, bob)?