Add basic type system with only integers

This commit adds static typing with signed and unsigned integers of 8,
16, 32 and 64 bits.

1 files changed, 43 insertions, 9 deletions

diff --git a/generate_error.go b/generate_error.go
index e89add2..88fe3f4 100644
--- a/generate_error.go
+++ b/generate_error.go
@@ -15,19 +15,35 @@ func (e errAlreadyDeclared) Error() string {
 	return fmt.Sprintf("%d: redeclaration of %q\n", e.line, e.name)
 }
 
+type undeclaredKind int
+
+const (
+	undeclaredVariable undeclaredKind = iota
+	undeclaredFunction
+	undeclaredType
+)
+
+func (u undeclaredKind) String() string {
+	switch u {
+	case undeclaredVariable:
+		return "variable"
+	case undeclaredFunction:
+		return "function"
+	case undeclaredType:
+		return "type"
+	default:
+		return "identifier"
+	}
+}
+
 type errUndeclared struct {
-	name   string
-	isFunc bool
-	line   int
+	name string
+	kind undeclaredKind
+	line int
 }
 
 func (e errUndeclared) Error() string {
-	kind := "variable"
-	if e.isFunc {
-		kind = "function"
-	}
-
-	return fmt.Sprintf("%d: undeclared %s %q\n", e.line, kind, e.name)
+	return fmt.Sprintf("%d: undeclared %s %q\n", e.line, e.kind, e.name)
 }
 
 type errImmutable struct {
@@ -38,3 +54,21 @@ type errImmutable struct {
 func (e errImmutable) Error() string {
 	return fmt.Sprintf("%d: cannot assign to constant %q\n", e.line, e.name)
 }
+
+type errTypeMismatch struct {
+	expected, got cerType
+	line          int
+}
+
+func (e errTypeMismatch) Error() string {
+	return fmt.Sprintf("%d: expected type %s, got %s", e.line, e.expected, e.got)
+}
+
+type errArgNumMismatch struct {
+	expected, got int
+	line          int
+}
+
+func (e errArgNumMismatch) Error() string {
+	return fmt.Sprintf("%d: function expects %d arguments, got %d", e.line, e.expected, e.got)
+}