Support NotEqual builtin

schala-lang/language/src/builtin.rs

@@ -33,6 +33,7 @@ pub enum Builtin {
     IOGetLine,
     Assignment,
     Concatenate,
+    NotEqual,
 }
 
 impl Builtin {
@@ -65,6 +66,7 @@ impl Builtin {
             Concatenate => ty!(StringT -> StringT -> StringT),
             Increment => ty!(Nat -> Int),
             Negate => ty!(Nat -> Int),
+            NotEqual => ty!(Nat -> Nat -> Bool),
         }
     }
 }
@@ -116,6 +118,7 @@ impl FromStr for Builtin {
             "<" => LessThan,
             "<=" => LessThanOrEqual,
             "==" => Equality,
+            "!=" => NotEqual,
             "=" => Assignment,
             "<=>" => Comparison,
             "print" => IOPrint,

schala-lang/language/src/tree_walk_eval/evaluator.rs

@@ -393,6 +393,12 @@ impl<'a, 'b> Evaluator<'a, 'b> {
                 (Equality, Lit(Bool(l)), Lit(Bool(r))) => Bool(l == r).into(),
                 (Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l == r).into(),
 
+                (NotEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l != r).into(),
+                (NotEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l != r).into(),
+                (NotEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l != r).into(),
+                (NotEqual, Lit(Bool(l)), Lit(Bool(r))) => Bool(l != r).into(),
+                (NotEqual, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l != r).into(),
+
                 (LessThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l < r).into(),
                 (LessThan, Lit(Int(l)), Lit(Int(r))) => Bool(l < r).into(),
                 (LessThan, Lit(Float(l)), Lit(Float(r))) => Bool(l < r).into(),

schala-lang/language/src/tree_walk_eval/test.rs

@@ -419,7 +419,7 @@ fn loops() {
     let source = r#"
 let mut a = 0
 let mut count = 0
-while !(a == 5) {
+while a != 5 {
     a = a + 1
     count = count + 100
 }