Add support for syntax blocks.

src/syntax/ast.rs

@@ -95,6 +95,7 @@ impl fmt::Display for Name {
 pub enum Statement {
     Binding(Location, Name, Expression),
     Print(Location, Name),
+    Expression(Expression),
 }
 
 impl PartialEq for Statement {
@@ -108,6 +109,10 @@ impl PartialEq for Statement {
                 Statement::Print(_, name2) => name1 == name2,
                 _ => false,
             },
+            Statement::Expression(e1) => match other {
+                Statement::Expression(e2) => e1 == e2,
+                _ => false,
+            },
         }
     }
 }

src/syntax/eval.rs

@@ -69,6 +69,8 @@ impl Statement {
                 stdout.push_str(&line);
                 Ok(Value::Void)
             }
+
+            Statement::Expression(e) => e.eval(stdout, env),
         }
     }
 }

src/syntax/parser.lalrpop

@@ -77,7 +77,7 @@ pub TopLevel: TopLevel = {
 }
 
 Function: TopLevel = {
-    "function" <opt_name:OptionalName> "(" <args:Arguments> OptionalComma ")" <exp:Expression> =>
+    "function" <opt_name:OptionalName> "(" <args:Arguments> OptionalComma ")" <exp:Expression> ";" =>
         TopLevel::Function(opt_name, args, exp),
 }
 
@@ -154,6 +154,10 @@ Statement: Statement = {
             Location::new(file_idx, ls..le),
             Name::new(v, Location::new(file_idx, name_start..name_end)),
         ),
+
+    // A statement can just be an expression.
+    <e: Expression> ";" =>
+        Statement::Expression(e),
 }
 
 // Expressions! Expressions are a little fiddly, because we're going to

src/syntax/pretty.rs

@@ -56,6 +56,7 @@ impl Statement {
                 .text("print")
                 .append(allocator.space())
                 .append(allocator.text(var.to_string())),
+            Statement::Expression(e) => e.pretty(allocator),
         }
     }
 }

src/syntax/validate.rs

@@ -177,6 +177,13 @@ impl Statement {
             Statement::Print(loc, var) => {
                 errors.push(Error::UnboundVariable(loc.clone(), var.to_string()))
             }
+
+            Statement::Expression(e) => {
+                let (mut exp_errors, mut exp_warnings) = e.validate(bound_variables);
+
+                errors.append(&mut exp_errors);
+                warnings.append(&mut exp_warnings);
+            }
         }
 
         (errors, warnings)