add examples

examples/hello_world.nix

@@ -0,0 +1,30 @@
+let
+  pkgs = import <nixpkgs> { overlays = [ (import ../pkgs) ]; };
+in {
+  bash = pkgs.writeBash "hello-world" ''
+    echo 'hello world'
+  '';
+  c = pkgs.writeC "hello-world"  {} ''
+    #include <stdio.h>
+    int main() {
+      printf("hello world\n");
+      return 0;
+    }
+  '';
+  dash = pkgs.writeDash "hello-world" ''
+    echo 'hello world'
+  '';
+  haskell = pkgs.writeHaskell "hello-world" [] ''
+    main = do
+      putStrLn "hello world"
+  '';
+  python2 = pkgs.writePython2 "hello-world" {} ''
+    print "hello world"
+  '';
+  python3 = pkgs.writePython3 "hello-world" {} ''
+    print("hello world")
+  '';
+  sed = pkgs.writeDash "sed-example" ''
+    echo xxx | ${pkgs.writeSed "hello-world" "s/xxx/hello world/"}
+  '';
+}

examples/simple.nix

@@ -0,0 +1,38 @@
+let
+  pkgs = import <nixpkgs> { overlays = [ (import ../pkgs) ]; };
+in {
+  bash = pkgs.writeBash "hello-world" ''
+   if [[ "test" == "test" ]]; then echo "bash features"; fi
+  '';
+  # cc -L/nix/store/...blah/lib -I/nix/store/...blah/include
+  dash = pkgs.writeDash "hello-world" ''
+   test '~' = '~' && echo 'dash features'
+  '';
+  haskell = pkgs.writeHaskell "hello-world" [ "acme-cuteboy" ] ''
+    import Acme.CuteBoy
+
+    main :: IO ()
+    main = print Rolf
+  '';
+  python2 = pkgs.writePython2 "hello-world" { deps = [ pkgs.python2Packages.pyyaml ]; } ''
+    import yaml
+
+    print yaml.load("""
+      - some
+      - random
+      - variables
+    """)
+  '';
+  python3 = pkgs.writePython3 "hello-world" { deps = [ pkgs.python3Packages.pyyaml ]; } ''
+    import yaml
+
+    print(yaml.load("""
+      - some
+      - random
+      - variables
+    """))
+  '';
+  sed = pkgs.writeDash "sed-example" ''
+    echo hello | ${pkgs.writeSed "hello-world" "s/hello/& world/"}
+  '';
+}