diff --git a/README.md b/README.md
index 5876baa..c4b1b42 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ wt :-1: :-1: wl
 .. (wsplit :-1: toFloat 4 >) filter (wl) each
 
 # 7. Print the total number of fields in all input lines
-#     { nf = nf + $NF }
+#     { nf = nf + NF }
 # END { print nf }
 .. (wsplit len) map sum wl
 
diff --git a/examples/awk/7.awk b/examples/awk/7.awk
new file mode 100644
index 0000000..9be2e6d
--- /dev/null
+++ b/examples/awk/7.awk
@@ -0,0 +1,2 @@
+{ nf = nf + NF }
+END { print nf }
diff --git a/examples/awk/7.msh b/examples/awk/7.msh
new file mode 100644
index 0000000..502366c
--- /dev/null
+++ b/examples/awk/7.msh
@@ -0,0 +1 @@
+.. (wsplit len) map sum wl
diff --git a/examples/awk/test.sh b/examples/awk/test.sh
index 44c11bd..c6eb9b5 100755
--- a/examples/awk/test.sh
+++ b/examples/awk/test.sh
@@ -32,5 +32,6 @@ else
 fi
 
 emp_test 6
+emp_test 7
 
 exit "$FAIL"
diff --git a/lib/std.msh b/lib/std.msh
index f4c5488..82bdf9f 100644
--- a/lib/std.msh
+++ b/lib/std.msh
@@ -53,6 +53,26 @@ def filter
     drop drop @filter-accum
 end
 
+# foldl (quote initial list -- result)
+def foldl
+    #  quote initial list
+    swap foldl-accum!  # Accumulator,
+    # quote list
+    swap foldl-quote! # Quote
+    # list
+    (
+        @foldl-accum swap # Accumulator item
+        @foldl-quote x # Execute quote
+        foldl-accum! # Update accumulator
+    ) each
+
+    @foldl-accum
+end
+
+# sum (list -- value)
+def sum
+    (+) 0 rot foldl
+end
 
 # .. (-- list[str]), equals kinda looks like lines.
 def .. stdin lines end
diff --git a/mshell/Lexer.go b/mshell/Lexer.go
index d7cdf31..12ab63d 100644
--- a/mshell/Lexer.go
+++ b/mshell/Lexer.go
@@ -181,7 +181,7 @@ func (t Token) ToJson() string {
 }
 
 func (t Token) DebugString() string {
-	return fmt.Sprintf("%d:%d: %s %s", t.Line, t.Column, t.Type, t.Lexeme)
+	return fmt.Sprintf("'%s'", t.Lexeme)
 }
 
 type Lexer struct {
diff --git a/tests/sum.msh b/tests/sum.msh
new file mode 100644
index 0000000..7b674c2
--- /dev/null
+++ b/tests/sum.msh
@@ -0,0 +1 @@
+[1 2 3 4] sum wl
diff --git a/tests/sum.msh.stdout b/tests/sum.msh.stdout
new file mode 100644
index 0000000..f599e28
--- /dev/null
+++ b/tests/sum.msh.stdout
@@ -0,0 +1 @@
+10