diff --git a/src/FormatNix.purs b/src/FormatNix.purs
index afcbac5..7323465 100644
--- a/src/FormatNix.purs
+++ b/src/FormatNix.purs
@@ -5,6 +5,8 @@ import Prelude
 import Data.Array as Array
 import Data.Either (Either(..))
 import Data.Foldable (class Foldable)
+import Data.Generic.Rep (class Generic)
+import Data.Generic.Rep.Show (genericShow)
 import Data.List (List(..), (:))
 import Data.List as List
 import Data.Maybe (Maybe(..))
@@ -74,6 +76,9 @@ data Expr
   -- Uri
   | Uri String
 derive instance eqExpr :: Eq Expr
+derive instance genericsExpr :: Generic Expr _
+instance showExpr :: Show Expr where
+  show x = genericShow x
 
 -- unknown node type, with the type string and text contents
 data UnknownExpr = Unknown String String
diff --git a/test/Main.purs b/test/Main.purs
index 84eaf37..4c8cc06 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -28,14 +28,16 @@ processInput filepath = do
     Right xs -> pure xs
     Left (Unknown tag str) -> do
       throwError $ Aff.error $  "Error: contained unknown: " <> tag <> "\n" <> str
+  let shown = Array.intercalate "\n" $ show <$> nodes
   let output = Array.intercalate "\n" $ printExpr <$> nodes
 
   log $ "printing " <> filepath <> ":"
   log string
+  log shown
   log output
   log ""
 
-  pure $ string <> "\n" <> output
+  pure $ string <> "\n" <> shown <> "\n" <> output
 
 main :: Effect Unit
 main = launchAff_ do
diff --git a/test/output.nix b/test/output.nix
index 2caee20..b6f1444 100644
--- a/test/output.nix
+++ b/test/output.nix
@@ -1,4 +1,6 @@
 (expression (comment) (function (formals (formal (identifier) (app (app (identifier) (spath)) (attrset)))) (let (bind (attrpath (identifier)) (select (identifier) (attrpath (identifier) (identifier) (identifier) (identifier)))) (bind (attrpath (identifier)) (function (identifier) (if (select (identifier) (attrpath (identifier) (identifier))) (string) (indented_string (interpolation (identifier)) (interpolation (identifier)))))) (app (select (identifier) (attrpath (identifier) (identifier))) (rec_attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (if (select (identifier) (attrpath (identifier) (identifier))) (app (select (identifier) (attrpath (identifier))) (attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)))) (app (select (identifier) (attrpath (identifier))) (attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)))))) (bind (attrpath (identifier)) (list (select (identifier) (attrpath (identifier))) (select (identifier) (attrpath (identifier))) (select (identifier) (attrpath (identifier))))) (bind (attrpath (identifier)) (app (select (identifier) (attrpath (identifier) (identifier))) (identifier))) (bind (attrpath (identifier)) (identifier)) (bind (attrpath (identifier)) (indented_string (interpolation (app (identifier) (identifier))))))))))
+(Comment "# https://github.com/justinwoo/easy-purescript-nix/blob/7255d015b80d28c7c6db655dda215535cb2d4b41/purs.nix")
+(SetFunction (Formals [(Formal (Identifier "pkgs") (Just (App (App (Identifier "import") (Spath "<nixpkgs>")) (AttrSet []))))]) (Let [(Bind (AttrPath "dynamic-linker") (Select (Identifier "pkgs") (AttrPath "stdenv.cc.bintools.dynamicLinker"))),(Bind (AttrPath "patchelf") (Function (Identifier "libPath") (If (Select (Identifier "pkgs") (AttrPath "stdenv.isDarwin")) (StringValue "\"\"") (StringIndented "''\n      chmod u+w $PURS\n      patchelf --interpreter ${dynamic-linker} --set-rpath ${libPath} $PURS\n      chmod u-w $PURS\n    ''"))))] [(App (Select (Identifier "pkgs") (AttrPath "stdenv.mkDerivation")) (RecAttrSet [(Bind (AttrPath "name") (StringValue "\"purs-simple\"")),(Bind (AttrPath "version") (StringValue "\"v0.12.3\"")),(Bind (AttrPath "src") (If (Select (Identifier "pkgs") (AttrPath "stdenv.isDarwin")) (App (Select (Identifier "pkgs") (AttrPath "fetchurl")) (AttrSet [(Bind (AttrPath "url") (StringValue "\"https://github.com/purescript/purescript/releases/download/v0.12.3/macos.tar.gz\"")),(Bind (AttrPath "sha256") (StringValue "\"1f916gv4fz571l4jvr15xjnsvjyy4nljv2ii9njwlm7k6yr5m0qn\""))])) (App (Select (Identifier "pkgs") (AttrPath "fetchurl")) (AttrSet [(Bind (AttrPath "url") (StringValue "\"https://github.com/purescript/purescript/releases/download/v0.12.3/linux64.tar.gz\"")),(Bind (AttrPath "sha256") (StringValue "\"1fad862a2sv4njxbbcfzibbi585m6is3ywb94nmjl8ax254baj3i\""))])))),(Bind (AttrPath "buildInputs") (List [(Select (Identifier "pkgs") (AttrPath "zlib")),(Select (Identifier "pkgs") (AttrPath "gmp")),(Select (Identifier "pkgs") (AttrPath "ncurses5"))])),(Bind (AttrPath "libPath") (App (Select (Identifier "pkgs") (AttrPath "lib.makeLibraryPath")) (Identifier "buildInputs"))),(Bind (AttrPath "dontStrip") (Identifier "true")),(Bind (AttrPath "installPhase") (StringIndented "''\n    mkdir -p $out/bin\n    PURS=\"$out/bin/purs\"\n\n    install -D -m555 -T purs $PURS\n    ${patchelf libPath}\n\n    mkdir -p $out/etc/bash_completion.d/\n    $PURS --bash-completion-script $PURS > $out/etc/bash_completion.d/purs-completion.bash\n  ''"))]))]))
 # https://github.com/justinwoo/easy-purescript-nix/blob/7255d015b80d28c7c6db655dda215535cb2d4b41/purs.nix
 
 { pkgs ? import <nixpkgs> {} }:
@@ -49,10 +51,12 @@ in pkgs.stdenv.mkDerivation rec {
 
 
 (expression (app (app (identifier) (path)) (attrset)))
+(App (App (Identifier "import") (Path "./build.nix")) (AttrSet []))
 import ./build.nix {}
 
 
 (expression (let (bind (attrpath (identifier)) (integer)) (bind (attrpath (identifier)) (integer)) (binary (unary (identifier)) (identifier))))
+(Let [(Bind (AttrPath "a") (Integer "123")),(Bind (AttrPath "b") (Integer "123"))] [(Binary (Unary "-" (Identifier "a")) "+" (Identifier "b"))])
 let
   a = 123;
 
@@ -62,12 +66,14 @@ in -a + b
 
 
 (expression (function (formals (formal (identifier) (string)) (formal (identifier) (string))) (binary (identifier) (identifier))))
+(SetFunction (Formals [(Formal (Identifier "foo") (Just (StringValue "\"foo\""))),(Formal (Identifier "bar") (Just (StringValue "\"bar\"")))]) (Binary (Identifier "foo") "+" (Identifier "bar")))
 { foo ? "foo", bar ? "bar" }:
 
 foo + bar
 
 
 (expression (function (formals (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier)) (formal (identifier))) (integer)))
+(SetFunction (Formals [(Formal (Identifier "apple") Nothing),(Formal (Identifier "bpple") Nothing),(Formal (Identifier "cpple") Nothing),(Formal (Identifier "dpple") Nothing),(Formal (Identifier "epple") Nothing),(Formal (Identifier "fpple") Nothing),(Formal (Identifier "gpple") Nothing),(Formal (Identifier "hpple") Nothing),(Formal (Identifier "ipple") Nothing),(Formal (Identifier "jpple") Nothing),(Formal (Identifier "kpple") Nothing),(Formal (Identifier "lpple") Nothing),(Formal (Identifier "mpple") Nothing),(Formal (Identifier "npple") Nothing),(Formal (Identifier "opple") Nothing),(Formal (Identifier "ppple") Nothing),(Formal (Identifier "qpple") Nothing),(Formal (Identifier "rpple") Nothing),(Formal (Identifier "spple") Nothing),(Formal (Identifier "tpple") Nothing),(Formal (Identifier "upple") Nothing),(Formal (Identifier "vpple") Nothing)]) (Integer "1"))
 {
   apple,
   bpple,
@@ -97,6 +103,7 @@ foo + bar
 
 
 (expression (attrset (inherit (parenthesized (identifier)) (attrs (identifier) (identifier) (identifier) (identifier))) (bind (attrpath (identifier)) (with (parenthesized (identifier)) (integer))) (inherit (parenthesized (identifier)) (attrs (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier) (identifier)))))
+(AttrSet [(Inherit [(Parens (Identifier "x")),(Attrs [(Identifier "a"),(Identifier "b"),(Identifier "c"),(Identifier "d")])]),(Bind (AttrPath "z") (With (Parens (Identifier "a")) (Integer "1"))),(Inherit [(Parens (Identifier "x")),(Attrs [(Identifier "apple"),(Identifier "bpple"),(Identifier "cpple"),(Identifier "dpple"),(Identifier "epple"),(Identifier "fpple"),(Identifier "gpple"),(Identifier "hpple"),(Identifier "ipple"),(Identifier "jpple"),(Identifier "kpple"),(Identifier "lpple"),(Identifier "mpple"),(Identifier "npple"),(Identifier "opple"),(Identifier "ppple"),(Identifier "qpple"),(Identifier "rpple"),(Identifier "spple"),(Identifier "tpple"),(Identifier "upple"),(Identifier "vpple")])])])
 {
   inherit (x) a b c d;
 
@@ -129,6 +136,8 @@ foo + bar
 
 
 (expression (comment) (function (formals (formal (identifier) (app (app (identifier) (spath)) (attrset)))) (app (app (identifier) (parenthesized (app (select (identifier) (attrpath (identifier))) (attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)))))) (attrset (inherit (attrs (identifier)))))))
+(Comment "# https://github.com/justinwoo/easy-purescript-nix/blob/7255d015b80d28c7c6db655dda215535cb2d4b41/psc-package2nix.nix")
+(SetFunction (Formals [(Formal (Identifier "pkgs") (Just (App (App (Identifier "import") (Spath "<nixpkgs>")) (AttrSet []))))]) (App (App (Identifier "import") (Parens (App (Select (Identifier "pkgs") (AttrPath "fetchFromGitHub")) (AttrSet [(Bind (AttrPath "owner") (StringValue "\"justinwoo\"")),(Bind (AttrPath "repo") (StringValue "\"psc-package2nix\"")),(Bind (AttrPath "rev") (StringValue "\"b4d6a834ac124440a503f0510b8a9de95532b16c\"")),(Bind (AttrPath "sha256") (StringValue "\"0g9fq4j472bcr1x5na6mzr3av95xhvdmnlns1ncvsl4kqa8ix2zr\""))])))) (AttrSet [(Inherit [(Attrs [(Identifier "pkgs")])])])))
 # https://github.com/justinwoo/easy-purescript-nix/blob/7255d015b80d28c7c6db655dda215535cb2d4b41/psc-package2nix.nix
 
 { pkgs ? import <nixpkgs> {} }:
@@ -144,6 +153,7 @@ import (pkgs.fetchFromGitHub {
 
 
 (expression (attrset (bind (attrpath (identifier)) (list (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string) (string))) (bind (attrpath (identifier)) (list (integer) (integer) (integer) (integer) (integer)))))
+(AttrSet [(Bind (AttrPath "a") (List [(StringValue "\"apple\""),(StringValue "\"bpple\""),(StringValue "\"cpple\""),(StringValue "\"dpple\""),(StringValue "\"epple\""),(StringValue "\"fpple\""),(StringValue "\"gpple\""),(StringValue "\"hpple\""),(StringValue "\"ipple\""),(StringValue "\"jpple\""),(StringValue "\"kpple\""),(StringValue "\"lpple\""),(StringValue "\"mpple\""),(StringValue "\"npple\""),(StringValue "\"opple\""),(StringValue "\"ppple\""),(StringValue "\"qpple\""),(StringValue "\"rpple\""),(StringValue "\"spple\""),(StringValue "\"tpple\""),(StringValue "\"upple\""),(StringValue "\"vpple\"")])),(Bind (AttrPath "b") (List [(Integer "1"),(Integer "2"),(Integer "3"),(Integer "4"),(Integer "5")]))])
 {
   a = [
     "apple"
@@ -175,6 +185,7 @@ import (pkgs.fetchFromGitHub {
 
 
 (expression (let (bind (attrpath (identifier)) (app (identifier) (parenthesized (app (select (identifier) (attrpath (identifier))) (uri))))) (bind (attrpath (identifier)) (app (app (identifier) (spath)) (attrset (bind (attrpath (identifier)) (list (identifier)))))) (with (identifier) (app (select (identifier) (attrpath (identifier))) (attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (list (select (identifier) (attrpath (identifier) (identifier) (identifier) (identifier))))))))))
+(Let [(Bind (AttrPath "moz_overlay") (App (Identifier "import") (Parens (App (Select (Identifier "builtins") (AttrPath "fetchTarball")) (Uri "https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz"))))),(Bind (AttrPath "nixpkgs") (App (App (Identifier "import") (Spath "<nixpkgs>")) (AttrSet [(Bind (AttrPath "overlays") (List [(Identifier "moz_overlay")]))])))] [(With (Identifier "nixpkgs") (App (Select (Identifier "stdenv") (AttrPath "mkDerivation")) (AttrSet [(Bind (AttrPath "name") (StringValue "\"moz_overlay_shell\"")),(Bind (AttrPath "buildInputs") (List [(Select (Identifier "nixpkgs") (AttrPath "latest.rustChannels.nightly.rust"))]))])))])
 let
   moz_overlay = import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz);
 
@@ -190,6 +201,7 @@ in with nixpkgs; stdenv.mkDerivation {
 
 
 (expression (let (bind (attrpath (identifier)) (app (identifier) (spath))) (comment) (with (identifier) (app (select (identifier) (attrpath (identifier))) (attrset (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (list)))))))
+(Let [(Bind (AttrPath "nixpkgs") (App (Identifier "import") (Spath "<nixpkgs>"))),(Comment "# some comment")] [(With (Identifier "nixpkgs") (App (Select (Identifier "stdenv") (AttrPath "mkDerivation")) (AttrSet [(Bind (AttrPath "name") (StringValue "\"something\"")),(Bind (AttrPath "buildInputs") (List []))])))])
 let
   nixpkgs = import <nixpkgs>;
 
@@ -203,6 +215,7 @@ in with nixpkgs; stdenv.mkDerivation {
 
 
 (expression (function (formals (formal (identifier)) (formal (identifier)) (ellipses)) (attrset (bind (attrpath (identifier) (identifier)) (string)))))
+(SetFunction (Formals [(Formal (Identifier "config") Nothing),(Formal (Identifier "pkgs") Nothing),Ellipses]) (AttrSet [(Bind (AttrPath "system.stateVersion") (StringValue "\"19.09\""))]))
 { config, pkgs, ... }:
 
 {
@@ -211,6 +224,7 @@ in with nixpkgs; stdenv.mkDerivation {
 
 
 (expression (let (bind (attrpath (identifier)) (string)) (bind (attrpath (identifier)) (string)) (indented_string (interpolation (identifier)) (interpolation (identifier)))))
+(Let [(Bind (AttrPath "hello") (StringValue "\"123\"")),(Bind (AttrPath "world") (StringValue "\"456\""))] [(StringIndented "''\n  first: ${hello} second: ${world}\n''")])
 let
   hello = "123";