diff --git a/gash/builtins.scm b/gash/builtins.scm
index a57e060..851dd14 100644
--- a/gash/builtins.scm
+++ b/gash/builtins.scm
@@ -46,10 +46,12 @@
             glob
             singlequotes
             doublequotes
-            expression
+            sequence
+            splice
             for
+            split
             substitution
-            sh-exec
+            script
             if-clause
 
             bg-command
@@ -475,16 +477,23 @@ Options:
 (define (doublequotes . o)
   (string-join (append-map glob  o) ""))
 
-(define (expression . args)
-  (append-map glob args))
+(define (sequence . args)
+  (apply append args))
 
-(define (for name expr body)
+(define (script . o)
+  o)
+
+(define (for name sequence body)
   (for-each (lambda (value)
               (assignment name value)
-              (body)) (expr)))
+              (body))
+            (sequence)))
 
-(define (substitution . commands)
-  (apply (@ (gash pipe) pipeline->string) (map cdr commands))) ;;HACK
+(define (split o)
+  ((compose string-tokenize string-trim-right) o))
+
+(define-syntax-rule (substitution commands)
+  (split (with-output-to-string (lambda _ commands))))
 
 (define-syntax if-clause
   (lambda (x)
diff --git a/gash/peg.scm b/gash/peg.scm
index e3839c5..9cbbb3d 100644
--- a/gash/peg.scm
+++ b/gash/peg.scm
@@ -117,7 +117,8 @@
 
      for-keyword      <   'for'
      in-keyword       <   'in'
-     for-clause       <-- for-keyword sp+ name (ws+ in-keyword pipeline)? sp* sequential-sep do-group
+     for-clause       <-- for-keyword sp+ name (ws+ in-keyword sequence)? sp* sequential-sep do-group
+     sequence         <-- (sp+ word)+
      do-keyword       <   'do'
      done-keyword     <   'done'
      do-group         <-  do-keyword ws* compound-list separator done-keyword
@@ -202,11 +203,10 @@
   (eq? o *unspecified*))
 
 (define (transform ast)
-  (when (> %debug-level 1)
+  (when (> %debug-level -1)
     (format (current-error-port) "transform ast=~s\n" ast))
   (match ast
-    (('script o ...) (map transform o))
-    (('substitution o) `(substitution ,@(transform o)))
+    (('script o ...) `(script ,@(map transform o)))
     (('pipeline o) (pk `(pipeline ,(transform o))))
     (('pipeline h t) (pk `(pipeline ,(transform h) ,@(map transform t))))
     (('command o ...) `(command ,@(map transform o)))
@@ -214,7 +214,17 @@
     (('name o) o)
     (('number o) o)
     (('assignment a b) `(lambda _ (assignment ,(transform a) ,(transform b))))
-    (('for-clause name expr do) `(for ,(transform name) (lambda _ ,(transform expr)) (lambda _ ,(transform do))))
+    (('for-clause name expr do)
+     `(for ,(transform name) (lambda _ ,(transform expr)) (lambda _ ,(transform do))))
+    (('sequence o ...)
+     `(sequence ,@(fold-right (lambda (o r)
+                                (cons
+                                 (match o
+                                   (('substitution x) (transform o))
+                                   (_ `(list ,(transform o))))
+                                 r))
+                              '() o)))
+    (('substitution o) `(substitution ,(transform o)))
     (('if-clause expr then) `(if-clause ,(transform expr) ,(transform then)))
     (('if-clause expr then else) `(if-clause ,(transform expr) ,(transform then) ,(transform else)))
     (('then-part o ...) `(begin ,@(map transform o)))