diff --git a/registry.cabal b/registry.cabal
--- a/registry.cabal
+++ b/registry.cabal
@@ -1,11 +1,11 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.35.2.
+-- This file has been generated from package.yaml by hpack version 0.37.0.
 --
 -- see: https://github.com/sol/hpack
 
 name:           registry
-version:        0.6.3.0
+version:        0.6.3.1
 synopsis:       data structure for assembling components
 description:    This library provides a "Registry" which is a data structure containing a list of functions and values representing dependencies in a directed acyclic graph. A `make` function can then be used to create a value of a specific type out of the registry.
                 You can start with the [README](https://github.com/etorreborre/registry/blob/master/README.md) for a full description of the library.
@@ -62,9 +62,9 @@
   ghc-options: -Wall -Wcompat -Wincomplete-record-updates -fhide-source-paths -fprint-potential-instances -optP-Wno-nonportable-include-path -Wincomplete-uni-patterns
   build-depends:
       base >=4.14 && <5
-    , containers >=0.5 && <0.7
+    , containers >=0.5 && <1.0
     , exceptions >=0.8 && <0.11
-    , hashable >=1.2 && <1.5
+    , hashable >=1.2 && <2.0
     , mmorph >=1.0 && <2
     , mtl >=2.0 && <3
     , multimap >=1.0 && <2
@@ -104,6 +104,8 @@
       Test.Data.Registry.THSpec
       Test.Tasty.Extensions
       Test.Tutorial.Application
+      Test.Tutorial.DatabaseLogger
+      Test.Tutorial.DatabaseLoggerExample
       Test.Tutorial.Exercise1
       Test.Tutorial.Exercise2
       Test.Tutorial.Exercise3
@@ -133,11 +135,11 @@
     , async <2.3
     , base >=4.14 && <5
     , bytestring <0.13
-    , containers >=0.5 && <0.7
+    , containers >=0.5 && <1.0
     , directory <1.4
     , exceptions >=0.8 && <0.11
     , generic-lens >=1.0 && <3.0
-    , hashable >=1.2 && <1.5
+    , hashable >=1.2 && <2.0
     , hedgehog >=1.0 && <3.0
     , io-memoize <1.2
     , mmorph >=1.0 && <2
diff --git a/test/Test/Tutorial/DatabaseLogger.hs b/test/Test/Tutorial/DatabaseLogger.hs
new file mode 100644
--- /dev/null
+++ b/test/Test/Tutorial/DatabaseLogger.hs
@@ -0,0 +1,46 @@
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE StrictData #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Test.Tutorial.DatabaseLogger where
+
+import Protolude hiding (log)
+
+-- | A Logger interface
+data Logger = Logger
+  { log :: Text -> Severity -> IO ()
+  }
+
+data Severity = Info | Error | Fatal
+  deriving (Eq, Ord, Show)
+
+-- | The production implementation
+newLogger :: Logger
+newLogger = Logger (\t s -> print ("[" <> show s <> "] " <> t))
+
+-- | 2 different ways to limit the severity for a Logger
+limitSeverity :: Severity -> Logger -> Logger
+limitSeverity at (Logger p) =
+  Logger (\t s ->
+    if s >= at then p t s
+    else pure ())
+
+newLimitedLogger :: Severity -> Logger
+newLimitedLogger at = limitSeverity at newLogger
+
+-- | This Logger doesn't log anything
+noLogger :: Logger
+noLogger = Logger (\_ _ -> pure ())
+
+-- | A database interface
+data Database = Database
+  { executeQuery :: Text -> IO ()
+  }
+
+-- | A production database using a Logger
+newDatabase :: Logger -> Database
+newDatabase logger = Database {..} where
+  executeQuery :: Text -> IO ()
+  executeQuery q = do
+    log logger ("executing query " <> q) Info
+    print "do it"
diff --git a/test/Test/Tutorial/DatabaseLoggerExample.hs b/test/Test/Tutorial/DatabaseLoggerExample.hs
new file mode 100644
--- /dev/null
+++ b/test/Test/Tutorial/DatabaseLoggerExample.hs
@@ -0,0 +1,36 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE PartialTypeSignatures #-}
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
+module Test.Tutorial.DatabaseLoggerExample where
+
+import Data.Registry
+import Test.Tutorial.DatabaseLogger
+
+prodRegistry =
+     fun newDatabase
+  <: fun newLogger
+
+prodDatabase = make @Database prodRegistry
+
+-- Don't log anything for those tests
+testRegistry1 =
+     fun noLogger
+  <: prodRegistry
+
+testDatabase1 = make @Database testRegistry1
+
+-- Only log some messages for those tests
+testRegistry2 =
+  tweak @Logger (limitSeverity Info) prodRegistry
+
+testDatabase2 = make @Database testRegistry2
+
+-- Only log some messages for those tests
+-- Specify the severity as a separate value
+testRegistry3 =
+     fun newLimitedLogger
+  <: val Info
+  <: prodRegistry
+
+testDatabase3 = make @Database testRegistry3