diff --git a/src/ast/Parse.go b/src/ast/Parse.go
index 20634e4..ea7c758 100644
--- a/src/ast/Parse.go
+++ b/src/ast/Parse.go
@@ -6,18 +6,20 @@ import (
 )
 
 // Parse generates an AST from a list of tokens.
-func Parse(tokens []token.Token, file *fs.File) (AST, error) {
+func Parse(tokens token.List, file *fs.File) (AST, error) {
 	nodes := make(AST, 0, len(tokens)/64)
 
-	err := eachInstruction(tokens, func(instruction token.List) error {
-		node, err := parseInstruction(instruction, file, nodes)
+	for tokens := range tokens.Instructions {
+		node, err := parseInstruction(tokens, file, nodes)
 
 		if node != nil {
 			nodes = append(nodes, node)
 		}
 
-		return err
-	})
+		if err != nil {
+			return nil, err
+		}
+	}
 
-	return nodes, err
+	return nodes, nil
 }
diff --git a/src/ast/eachInstruction.go b/src/ast/eachInstruction.go
deleted file mode 100644
index 0bed958..0000000
--- a/src/ast/eachInstruction.go
+++ /dev/null
@@ -1,69 +0,0 @@
-package ast
-
-import "git.urbach.dev/cli/q/src/token"
-
-// eachInstruction calls the function on each AST node.
-func eachInstruction(tokens token.List, call func(token.List) error) error {
-	start := 0
-	groupLevel := 0
-	blockLevel := 0
-
-	for i, t := range tokens {
-		switch t.Kind {
-		case token.NewLine:
-			if start == i {
-				start = i + 1
-				continue
-			}
-
-			if groupLevel > 0 || blockLevel > 0 {
-				continue
-			}
-
-			err := call(tokens[start:i])
-
-			if err != nil {
-				return err
-			}
-
-			start = i + 1
-
-		case token.GroupStart:
-			groupLevel++
-
-		case token.GroupEnd:
-			groupLevel--
-
-		case token.BlockStart:
-			blockLevel++
-
-		case token.BlockEnd:
-			blockLevel--
-
-			if groupLevel > 0 || blockLevel > 0 {
-				continue
-			}
-
-			err := call(tokens[start : i+1])
-
-			if err != nil {
-				return err
-			}
-
-			start = i + 1
-
-		case token.EOF:
-			if start < i {
-				return call(tokens[start:i])
-			}
-
-			return nil
-		}
-	}
-
-	if start < len(tokens) {
-		return call(tokens[start:])
-	}
-
-	return nil
-}
diff --git a/src/ast/parseCases.go b/src/ast/parseCases.go
index dbb5412..2ea4cf1 100644
--- a/src/ast/parseCases.go
+++ b/src/ast/parseCases.go
@@ -10,11 +10,11 @@ import (
 func parseCases(tokens token.List, file *fs.File) ([]Case, error) {
 	var cases []Case
 
-	err := eachInstruction(tokens, func(caseTokens token.List) error {
+	for caseTokens := range tokens.Instructions {
 		blockStart, _, body, err := block(caseTokens, file)
 
 		if err != nil {
-			return err
+			return nil, err
 		}
 
 		conditionTokens := caseTokens[:blockStart]
@@ -30,9 +30,7 @@ func parseCases(tokens token.List, file *fs.File) ([]Case, error) {
 			Condition: condition,
 			Body:      body,
 		})
+	}
 
-		return nil
-	})
-
-	return cases, err
+	return cases, nil
 }
diff --git a/src/token/Instructions.go b/src/token/Instructions.go
new file mode 100644
index 0000000..183d6db
--- /dev/null
+++ b/src/token/Instructions.go
@@ -0,0 +1,61 @@
+package token
+
+// Instructions yields on each AST node.
+func (list List) Instructions(yield func(List) bool) {
+	start := 0
+	groupLevel := 0
+	blockLevel := 0
+
+	for i, t := range list {
+		switch t.Kind {
+		case NewLine:
+			if start == i {
+				start = i + 1
+				continue
+			}
+
+			if groupLevel > 0 || blockLevel > 0 {
+				continue
+			}
+
+			if !yield(list[start:i]) {
+				return
+			}
+
+			start = i + 1
+
+		case GroupStart:
+			groupLevel++
+
+		case GroupEnd:
+			groupLevel--
+
+		case BlockStart:
+			blockLevel++
+
+		case BlockEnd:
+			blockLevel--
+
+			if groupLevel > 0 || blockLevel > 0 {
+				continue
+			}
+
+			if !yield(list[start : i+1]) {
+				return
+			}
+
+			start = i + 1
+
+		case EOF:
+			if start < i {
+				yield(list[start:i])
+			}
+
+			return
+		}
+	}
+
+	if start < len(list) {
+		yield(list[start:])
+	}
+}
diff --git a/src/token/Instructions_test.go b/src/token/Instructions_test.go
new file mode 100644
index 0000000..cb06501
--- /dev/null
+++ b/src/token/Instructions_test.go
@@ -0,0 +1,20 @@
+package token_test
+
+import (
+	"testing"
+
+	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/go/assert"
+)
+
+func TestInstructions(t *testing.T) {
+	src := []byte("a := 1\nb := 2\n")
+	tokens := token.Tokenize(src)
+	nodes := []string{}
+
+	for param := range tokens.Instructions {
+		nodes = append(nodes, param.Text(src))
+	}
+
+	assert.DeepEqual(t, nodes, []string{"a:=1", "b:=2"})
+}