2015-09-24: add sh example

add sh example

diff --git a/examples/sh.w b/examples/sh.w
new file mode 100755
--- /dev/null
+++ b/examples/sh.w
@@ -0,0 +1,25 @@
+#!/usr/bin/env sh
+# -*- wisp -*-
+exec guile -L $(dirname $(dirname $(realpath "$0"))) --language=wisp -e '(@@ (examples sh) main)' -s "$0" "$@"
+; !#
+
+;; simplest way to run shell commands
+
+define-module : examples sh
+              . #:export : sh
+
+use-modules : srfi srfi-1
+
+define : ->string thing
+  if : symbol? thing
+    symbol->string thing
+    format #f "\"~A\"" thing
+
+define : run-me . args
+  system : string-join : map ->string args
+
+define-syntax-rule : sh args ...
+  apply run-me : quote : args ...
+
+define : main args
+  sh echo foo | sed s/o/u/