feat: expression

Makefile

@@ -4,8 +4,11 @@ it:
 	@ go build -o ${BINARY_NAME} ./cmd/lambda
 	@ chmod +x ${BINARY_NAME}
 
-ex: it
+simple: it
 	@ ./lambda.exe - < ./samples/simple.txt
 
-v: it
-	@ ./lambda.exe -v - < ./samples/simple.txt
+thunk: it
+	@ ./lambda.exe - < ./samples/thunk.txt
+
+saccharine: it
+	@ ./lambda.exe - < ./samples/saccharine.txt

pkg/saccharine/ast/expression.go

@@ -20,6 +20,10 @@ type Atom struct {
 	Name string
 }
 
+func (Abstraction) IsExpression() {}
+func (Application) IsExpression() {}
+func (Atom) IsExpression()        {}
+
 /** ------------------------------------------------------------------------- */
 
 func NewAbstraction(parameter []string, body Expression) *Abstraction {
@@ -33,9 +37,3 @@ func NewApplication(abstraction Expression, arguments []Expression) *Application
 func NewAtom(name string) *Atom {
 	return &Atom{Name: name}
 }
-
-/** ------------------------------------------------------------------------- */
-
-func (a Abstraction) IsExpression() {}
-func (a Application) IsExpression() {}
-func (v Atom) IsExpression()        {}

pkg/saccharine/ast/program.go

@@ -0,0 +1,5 @@
+package ast
+
+type Program struct {
+	Statements []Statement
+}

pkg/saccharine/ast/statement.go

@@ -0,0 +1,28 @@
+package ast
+
+type Statement interface {
+	IsStatement()
+}
+
+/** ------------------------------------------------------------------------- */
+
+type LetStatement struct {
+	Variable string
+	Value    Expression
+}
+
+type MethodStatement struct {
+	Name       string
+	Parameters []string
+	Body       Expression
+}
+
+type DeclareStatement struct {
+	Value Expression
+}
+
+func (LetStatement) IsStatement()     {}
+func (MethodStatement) IsStatement()  {}
+func (DeclareStatement) IsStatement() {}
+
+/** ------------------------------------------------------------------------- */

pkg/saccharine/tokenizer.go

@@ -69,7 +69,7 @@ func getToken(i *iterator.Iterator[rune]) (*token.Token, error) {
 		return token.NewAtom(string(atom), index), nil
 	}
 
-	return nil, fmt.Errorf("unknown character '%v'", letter)
+	return nil, fmt.Errorf("unknown character '%v'", string(letter))
 }
 
 // Parses a list of runes into tokens. All error encountered are returned, as well.

samples/saccharine.txt

@@ -1,9 +1,9 @@
 0 := \f x.x
-inc n := \f x.f (n f x)
-add n m := m inc n
-mult n m := m (n f)
-exp m n := m n
+(inc n) := \f x.(f (n f x))
+(add n m) := (m inc n)
+(mult n m) := (m (n f))
+(exp m n) := (m n)
 
 # This is the final output.
 5 := (inc (inc (inc (inc (inc 0)))))
-exp 5 5
+(exp 5 5)

samples/thunk.txt

@@ -0,0 +1 @@
+(\.VALUE anything)