Compile function environments

1 files changed, 22 insertions, 1 deletions

diff --git a/pkg/lang/compiler/scope/symbol.go b/pkg/lang/compiler/scope/symbol.go
index 3b50108..b87d5aa 100644
--- a/pkg/lang/compiler/scope/symbol.go
+++ b/pkg/lang/compiler/scope/symbol.go
@@ -10,17 +10,30 @@ func (id SymbolID) SymbolKind() SymbolKind {
 	return id.symbolKind
 }
 
+func (id SymbolID) ScopeID() ScopeID {
+	return id.scopeID
+}
+
+func (id SymbolID) IndexInScope() int {
+	return id.indexInScope
+}
+
 type SymbolKind int
 
 const (
 	// A variable symbol is bound to a local on the stack.
 	SymbolKindVariable SymbolKind = iota
+	// An env symbol is bound to a local on the stack, outside of the function's scope.
+	// Emitted at lookup time, so the SymbolScope has no array for them.
+	SymbolKindEnv SymbolKind = iota
 )
 
 func (s SymbolKind) String() string {
 	switch s {
 	case SymbolKindVariable:
 		return "variable"
+	case SymbolKindEnv:
+		return "env"
 	default:
 		panic("unknown symbol kind")
 	}
@@ -36,7 +49,7 @@ func (s Symbol[D]) Data() D {
 }
 
 type SymbolData interface {
-	SymbolVariable
+	SymbolVariable | SymbolEnv
 }
 
 type SymbolVariable struct {
@@ -46,3 +59,11 @@ type SymbolVariable struct {
 func (sv SymbolVariable) LocalIndex() int {
 	return sv.localIndex
 }
+
+type SymbolEnv struct {
+	indexInEnv int
+}
+
+func (se SymbolEnv) IndexInEnv() int {
+	return se.indexInEnv
+}