feat: tokenizer accepts braces, line terminator, and equal sign

pkg/saccharine/ast/expression.go

@@ -20,9 +20,15 @@ type Atom struct {
 	Name string
 }
 
+type Clause struct {
+	Statements []Statement
+	Returns    Expression
+}
+
 func (Abstraction) IsExpression() {}
 func (Application) IsExpression() {}
 func (Atom) IsExpression()        {}
+func (Clause) IsExpression()      {}
 
 /** ------------------------------------------------------------------------- */
 
@@ -37,3 +43,7 @@ func NewApplication(abstraction Expression, arguments []Expression) *Application
 func NewAtom(name string) *Atom {
 	return &Atom{Name: name}
 }
+
+func NewClause(statements []Statement, returns Expression) *Clause {
+	return &Clause{Statements: statements, Returns: returns}
+}