Boolean patterns

schala-lang/src/eval.rs

@@ -236,23 +236,24 @@ impl<'a> State<'a> {
                 return inner_state.block(alt.item)
               }
             }
-            return Err(format!("Failed pattern match"));
+            return Err(format!("PrimObject failed pattern match"));
           },
           Node::PrimTuple { .. } => Err(format!("Tuples not implemented")), //TODO make a distinction between not yet implemented and an actual runtime error
           Node::Expr(e) => {
             for alt in alternatives {
-              match alt.guard {
-                Some(ref guard_expr) if alt.tag.is_none() => {
+              match (alt.guard, alt.tag) {
+                (Some(ref guard_expr), None) => {
                   match self.expression(guard_expr.clone().to_node())? {
                     Node::Expr(Expr::Lit(::reduced_ast::Lit::Bool(true))) => 
                       return self.block(alt.item),
                     _ => continue,
                   }
                 },
-                _ => ()
+                (None, None) => return self.block(alt.item),
+                _ => return Err(format!("Shouldn't match an expr against a pattern"))
               }
             }
-            return Err(format!("Failed pattern match"));
+            return Err(format!("Expr Failed pattern match"));
           }
         },
         UnimplementedSigilValue => Err(format!("Sigil value eval not implemented"))
@@ -529,4 +530,22 @@ if a { is 15 -> "x", is 10 -> "y" }
 "#;
   test_in_fresh_env!(source, "\"y\"");
   }
+
+  #[test]
+  fn boolean_pattern() {
+    let source = r#"
+let a = true
+if a { is true -> "x", is false -> "y" }
+"#;
+    test_in_fresh_env!(source, "\"x\"");
+  }
+
+  #[test]
+  fn boolean_pattern_2() {
+    let source = r#"
+let a = false
+if a { is true -> "x", is false -> "y" }
+"#;
+    test_in_fresh_env!(source, "\"y\"");
+  }
 }

schala-lang/src/reduced_ast.rs

@@ -240,7 +240,20 @@ impl Pattern {
         },
         PatternLiteral::StringPattern(_s) => unimplemented!(),
         PatternLiteral::BoolPattern(b) =>  {
-          unimplemented!()
+          let guard = Some(if *b {
+            *cond.clone()
+          } else {
+            Expr::Call {
+              f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("!".to_string())))),
+              args: vec![*cond.clone()]
+            }
+          });
+          Alternative {
+            tag: None,
+            guard,
+            bound_vars: vec![],
+            item
+          }
         },
         PatternLiteral::VarPattern(var) => match symbol_table.lookup_by_name(var) {
           Some(symbol) => handle_symbol(symbol, &vec![], item),