diff --git a/tokenize.cm b/tokenize.cm
index c49d9019..cfae5df2 100644
--- a/tokenize.cm
+++ b/tokenize.cm
@@ -1,11 +1,6 @@
 var tokenize = function(src, filename) {
   var len = length(src)
-  var cp = []
-  var _i = 0
-  while (_i < len) {
-    push(cp, codepoint(src[_i]))
-    _i = _i + 1
-  }
+  var cp = array(array(src), codepoint)
 
   var pos = 0
   var row = 0
@@ -148,46 +143,45 @@ var tokenize = function(src, filename) {
   }
 
   var substr = function(start, end) {
-    var s = ""
-    var i = start
-    while (i < end) {
-      s = s + character(cp[i])
-      i = i + 1
-    }
-    return s
+    return text(src, start, end)
   }
 
   var read_string = function(quote_cp) {
     var start = pos
     var start_row = row
     var start_col = col
-    var value = ""
+    var parts = []
+    var run_start = 0
     var esc = 0
     adv() // skip opening quote
+    run_start = pos
     while (pos < len && pk() != quote_cp) {
       if (pk() == CP_BSLASH) {
+        if (pos > run_start) push(parts, text(src, run_start, pos))
         adv()
         esc = adv()
-        if (esc == CP_n) { value = value + "\n" }
-        else if (esc == CP_t) { value = value + "\t" }
-        else if (esc == CP_r) { value = value + "\r" }
-        else if (esc == CP_BSLASH) { value = value + "\\" }
-        else if (esc == CP_SQUOTE) { value = value + "'" }
-        else if (esc == CP_DQUOTE) { value = value + "\"" }
-        else if (esc == CP_0) { value = value + character(0) }
-        else if (esc == CP_BACKTICK) { value = value + "`" }
-        else if (esc == CP_u) { value = value + read_unicode_escape() }
-        else { value = value + character(esc) }
+        if (esc == CP_n) { push(parts, "\n") }
+        else if (esc == CP_t) { push(parts, "\t") }
+        else if (esc == CP_r) { push(parts, "\r") }
+        else if (esc == CP_BSLASH) { push(parts, "\\") }
+        else if (esc == CP_SQUOTE) { push(parts, "'") }
+        else if (esc == CP_DQUOTE) { push(parts, "\"") }
+        else if (esc == CP_0) { push(parts, character(0)) }
+        else if (esc == CP_BACKTICK) { push(parts, "`") }
+        else if (esc == CP_u) { push(parts, read_unicode_escape()) }
+        else { push(parts, character(esc)) }
+        run_start = pos
       } else {
-        value = value + character(adv())
+        adv()
       }
     }
+    if (pos > run_start) push(parts, text(src, run_start, pos))
     if (pos < len) adv() // skip closing quote
     push(tokens, {
       kind: "text", at: start,
       from_row: start_row, from_column: start_col,
       to_row: row, to_column: col,
-      value: value
+      value: text(parts)
     })
   }
 
@@ -195,49 +189,54 @@ var tokenize = function(src, filename) {
     var start = pos
     var start_row = row
     var start_col = col
-    var value = ""
+    var parts = []
+    var run_start = 0
     var depth = 0
     var tc = 0
     var q = 0
+    var interp_start = 0
     adv() // skip opening backtick
+    run_start = pos
     while (pos < len && pk() != CP_BACKTICK) {
       if (pk() == CP_BSLASH && pos + 1 < len) {
-        value = value + character(adv())
-        value = value + character(adv())
+        if (pos > run_start) push(parts, text(src, run_start, pos))
+        push(parts, text(src, pos, pos + 2))
+        adv(); adv()
+        run_start = pos
       } else if (pk() == CP_DOLLAR && pos + 1 < len && pk_at(1) == CP_LBRACE) {
-        value = value + character(adv()) // $
-        value = value + character(adv()) // {
+        if (pos > run_start) push(parts, text(src, run_start, pos))
+        interp_start = pos
+        adv(); adv() // $ {
         depth = 1
         while (pos < len && depth > 0) {
           tc = pk()
-          if (tc == CP_LBRACE) { depth = depth + 1; value = value + character(adv()) }
+          if (tc == CP_LBRACE) { depth = depth + 1; adv() }
           else if (tc == CP_RBRACE) {
             depth = depth - 1
-            if (depth > 0) { value = value + character(adv()) }
-            else { value = value + character(adv()) }
+            adv()
           }
           else if (tc == CP_SQUOTE || tc == CP_DQUOTE || tc == CP_BACKTICK) {
             q = adv()
-            value = value + character(q)
             while (pos < len && pk() != q) {
-              if (pk() == CP_BSLASH && pos + 1 < len) {
-                value = value + character(adv())
-              }
-              value = value + character(adv())
+              if (pk() == CP_BSLASH && pos + 1 < len) adv()
+              adv()
             }
-            if (pos < len) { value = value + character(adv()) }
-          } else { value = value + character(adv()) }
+            if (pos < len) adv()
+          } else { adv() }
         }
+        push(parts, text(src, interp_start, pos))
+        run_start = pos
       } else {
-        value = value + character(adv())
+        adv()
       }
     }
+    if (pos > run_start) push(parts, text(src, run_start, pos))
     if (pos < len) adv() // skip closing backtick
     push(tokens, {
       kind: "text", at: start,
       from_row: start_row, from_column: start_col,
       to_row: row, to_column: col,
-      value: value
+      value: text(parts)
     })
   }
 
@@ -344,14 +343,13 @@ var tokenize = function(src, filename) {
     var start = pos
     var start_row = row
     var start_col = col
-    var val = ""
     var i = 0
-    while (i < count) { val = val + character(adv()); i = i + 1 }
+    while (i < count) { adv(); i = i + 1 }
     push(tokens, {
       kind: "name", at: start,
       from_row: start_row, from_column: start_col,
       to_row: row, to_column: col,
-      value: val
+      value: text(src, start, pos)
     })
   }
 
diff --git a/tokenize.mach b/tokenize.mach
index 7e12ea62..a8d0e522 100644
Binary files a/tokenize.mach and b/tokenize.mach differ