diff --git a/README.md b/README.md
index 11c1cfc..d46e24b 100644
--- a/README.md
+++ b/README.md
@@ -27,33 +27,33 @@ A command declares
 For example:
 
 ``` toit
-import cli
+import cli show *
 
 main args/List:
-  command := cli.Command "my-app"
+  command := Command "my-app"
     --help="My app does something."
     --options=[
-      cli.Option "some-option"
+      Option "some-option"
         --help="This is an option."
         --required,
-      cli.Flag "some-flag"
+      Flag "some-flag"
         --short-name="f"
         --help="This is a flag.",
     ]
     --rest=[
-      cli.Option "rest-arg"
+      Option "rest-arg"
         --help="This is a rest argument."
         --multi,
     ]
     --examples=[
-      cli.Example "Do something with the flag:"
+      Example "Do something with the flag:"
           --arguments="--some-option=foo --no-some-flag rest1 rest1",
     ]
-    --run=:: | app/cli.Application parsed/cli.Parsed |
-      print parsed["some-option"]
-      print parsed["some-flag"]
-      print parsed["rest-arg"]  // A list.
-      app.ui.result "Computed result"
+    --run=:: | invocation/Invocation |
+      print invocation["some-option"]
+      print invocation["some-flag"]
+      print invocation["rest-arg"]  // A list.
+      invocation.cli.ui.result "Computed result"
 
   command.run args
 ```
@@ -78,15 +78,15 @@ Subcommands are defined by adding a `Command` object as child to another command
 For example:
 
 ``` toit
-import cli
+import cli show *
 
 main args/List:
-  command := cli.Command "my-app"
+  command := Command "my-app"
     --help="My app does something."
 
-  sub := cli.Command "subcommand"
+  sub := Command "subcommand"
     --help="This is a subcommand."
-    --run=:: | app/cli.Application parsed/cli.Parsed |
+    --run=:: | invocation/Invocation |
       print "This is a subcommand."
   command.add sub
 
@@ -117,17 +117,24 @@ of the library for a complete list.
 
 Users are encouraged to extend the `cli.Option` class and create their own typed options.
 
-## Application
+## Invocation
 
 A call to `command.run` parses the given arguments and then executes the
-appropriate lambda. The lambda receives two arguments: an `Application` object and a
-`Parsed` object.
+appropriate lambda. The lambda receives one argument: an `Invocation` object.
 
-The `Application` object contains getters for the cache, config, and UI objects.
+The `Invocation` object contains:
+- `cli`: A `Cli` object that contains common functionality for CLI applications, like
+  the `cache`, `config`, and `ui` objects. It is common to pass this object to
+  functions that are called from the lambda.
+- `parameters`: An object that contains the parsed options and rest arguments. The
+  `Invocation` object has a shortcut operator `[]` that forwards to the `parameters`.
+- `path`: A list of strings that contains the path to the command that was called.
+- `command`: The command that was called.
 
 ### Cache
 
-The cache is a simple key-value store that persists between runs. It is typically
+The cache is a simple key-value store that persists between runs. Cached data may
+be removed at any point without major implications to the user. It is typically
 stored in `~/.cache/<command-name>`. Environment variables, such as `$XDG_CACHE_HOME`, or
 `$APP_CACHE_DIR` (where `APP` is the capitalized name) can be used to change the
 location of the cache. See the documentation of the `cache` library for more details.
@@ -139,13 +146,12 @@ The cache can either store bytes, or handle paths to cached folders.
 The cache can store bytes. For example:
 
 ``` toit
-import cli
-import cli.cache as cli
+import cli show Cli FileStore
 
-store-bytes app/cli.Application:
-  cache := app.cache
+store-bytes cli/Cli:
+  cache := cli.cache
 
-  data := cache.get "my-key": | store/cli.FileStore |
+  data := cache.get "my-key": | store/FileStore |
     // Block that is called when the key is not found.
     // The returned data is stored in the cache.
     print "Data is not cached. Computing it."
@@ -158,14 +164,13 @@ The `FileStore` class provides convenience methods to store data. For example, i
 allows to store (either copy or move) existing files:
 
 ``` toit
-import cli
-import cli.cache as cli
+import cli show Cli FileStore
 import host.file
 
-store-from-file app/cli.Application:
-  cache := app.cache
+store-from-file cli/Cli:
+  cache := cli.cache
 
-  data := cache.get "my-file-key": | store/cli.FileStore |
+  data := cache.get "my-file-key": | store/FileStore |
     // Block that is called when the key is not found.
     print "Data is not cached. Computing it."
     store.with-tmp-directory: | tmp-dir |
@@ -184,13 +189,13 @@ directory in the cache structure. The cache class has the
 `get-directory-path` method for this use case:
 
 ``` toit
-import cli
-import cli.cache as cli
+import cli show Cli DirectoryStore
+import host.file
 
-store-directory app/cli.Application:
-  cache := app.cache
+store-directory cli/Cli:
+  cache := cli.cache
 
-  directory := cache.get-directory-path "my-dir-key": | store/cli.DirectoryStore |
+  directory := cache.get-directory-path "my-dir-key": | store/DirectoryStore |
     // Block that is called when the key is not found.
     // The returned directory is stored in the cache.
     print "Directory is not cached. Computing it."
@@ -216,11 +221,10 @@ strings, and the values can be any json-serializable object.
 When modifying a configuration it is necessary to `write` the changes back to disk.
 
 ``` toit
-import cli
-import cli.config as cli
+import cli show Cli Config
 
-config-example app/cli.Application:
-  config := app.config
+config-example cli/Cli:
+  config := cli.config
 
   print "old value: $(config.get "my-key")"
 
@@ -231,8 +235,8 @@ config-example app/cli.Application:
 Keys are split at "." to allow for nested values. For example:
 
 ``` toit
-dotted-example app/cli.Application:
-  config := app.config
+dotted-example cli/Cli:
+  config := cli.config
 
   print "old value: $(config.get "super-key.sub-key")"
 
@@ -266,18 +270,18 @@ add the following options to the root command:
   --verbosity-level debug|info|verbose|quiet|silent  Specify the verbosity level. (default: info)
 ```
 
-A corresponding UI object is then available in the `Application` object. Whenever the
+A corresponding UI object is then available in the `Cli` object. Whenever the
 program wants to output something, it should use the `ui` object.
 
 ``` toit
-import cli
+import cli show Cli
 
-some-chatty-method app/cli.Application:
-  ui := app.ui
+some-chatty-method cli/Cli:
+  ui := cli.ui
   ui.debug "This is a debug message."
   ui.verbose "This is a verbose message."
-  ui.info "This is an info message."
-  ui.warning "This is a warning message."
+  ui.inform "This is an information message."
+  ui.warn "This is a warning message."
   ui.error "This is an error message."
   ui.interactive "This is an interactive message."
   ui.result "This is a result message."
@@ -303,22 +307,21 @@ Developers are encouraged to use the `ui.emit --structured` method to emit struc
 data. This is especially true for the result message.
 
 ``` toit
-import cli
-import cli.ui as cli
+import cli show *
 
 main args:
-  cmd := cli.Command "my-app"
+  cmd := Command "my-app"
     --help="My app does something."
-    --run=:: | app/cli.Application parsed/cli.Parsed |
-      run-app app parsed
+    --run=:: run it
 
-run-app app/cli.Application parsed/cli.Parsed:
-  ui := app.ui
+run invocation/Invocation:
+  ui := invocation.cli.ui
   ui.emit
       // Block that is invoked if structured data is needed.
       --structured=: {
         "result": "Computed result"
       }
+      // Block that is invoked if text data is needed.
       --text=: "Computed result as text message."
 ```
 
@@ -330,6 +333,9 @@ The `Ui` class has furthermore convenience methods to print tables, maps and lis
 Typically, these methods are used for result messages, but they can be used for
 other messages as well.
 
+The shorthands `ui.info`, `ui.debug`, also dispatch to these methods if they receive a
+  table (list of lists), map or list.
+
 See the documentation of the `ui` library for more details.
 
 ## Features and bugs
diff --git a/examples/cache.toit b/examples/cache.toit
new file mode 100644
index 0000000..1a5ee57
--- /dev/null
+++ b/examples/cache.toit
@@ -0,0 +1,53 @@
+// Copyright (C) 2024 Toitware ApS. All rights reserved.
+// Use of this source code is governed by an MIT-style license that can be
+// found in the package's LICENSE file.
+
+import cli show *
+import host.file
+
+store-bytes cli/Cli:
+  cache := cli.cache
+
+  data := cache.get "my-key": | store/FileStore |
+    // Block that is called when the key is not found.
+    // The returned data is stored in the cache.
+    print "Data is not cached. Computing it."
+    store.save #[0x01, 0x02, 0x03]
+
+  print data  // Prints #[0x01, 0x02, 0x03].
+
+store-directory cli/Cli:
+  cache := cli.cache
+
+  directory := cache.get-directory-path "my-dir-key": | store/DirectoryStore |
+    // Block that is called when the key is not found.
+    // The returned directory is stored in the cache.
+    print "Directory is not cached. Computing it."
+    store.with-tmp-directory: | tmp-dir |
+      // Create a few files with some data.
+      file.write-content --path="$tmp-dir/data1.txt" "Hello world"
+      file.write-content --path="$tmp-dir/data2.txt" "Bonjour monde"
+      store.move tmp-dir
+
+  print directory  // Prints the path to the directory.
+
+main args:
+  // Uses the application name "cli-example" which will be used
+  // to compute the path of the cache directory.
+  root-cmd := Command "cli-example"
+      --help="""
+          An example application demonstrating the file-cache.
+          """
+      --options=[
+        OptionEnum "mode" ["file", "directory"]
+            --help="Store a file in the cache."
+            --required,
+      ]
+      --run=:: run it
+  root-cmd.run args
+
+run invocation/Invocation:
+  if invocation["mode"] == "file":
+    store-bytes invocation.cli
+  else:
+    store-directory invocation.cli
diff --git a/examples/main.toit b/examples/commands.toit
similarity index 65%
rename from examples/main.toit
rename to examples/commands.toit
index 98152f1..3993247 100644
--- a/examples/main.toit
+++ b/examples/commands.toit
@@ -2,8 +2,7 @@
 // Use of this source code is governed by an MIT-style license that can be
 // found in the package's LICENSE file.
 
-import cli
-import cli.ui as cli
+import cli show *
 
 /**
 Creates a command-line executable that parses the command-line arguments and
@@ -18,7 +17,7 @@ It can not be used to manage the fleet, for example
   by adding or removing devices.
 
 Usage:
-  examples/main.toit <command>
+  examples/main.toit <command> [<options>]
 
 Commands:
   device  Manage a particular device.
@@ -26,17 +25,20 @@ Commands:
   status  Shows the status of the fleet.
 
 Options:
-  -h, --help  Show help for this command.
+  -h, --help                                             Show help for this command.
+      --output-format text|json                          Specify the format used when printing to the console. (default: text)
+      --verbose                                          Enable verbose output. Shorthand for --verbosity-level=verbose.
+      --verbosity-level debug|info|verbose|quiet|silent  Specify the verbosity level. (default: info)
 
 Examples:
-  # Do a soft-reset of device 'foo':
-  fleet_manager device --device=foo reset -m soft
+  # Uploads the file 'foo.data' to the device 'foo':
+  main.toit device --device=foo upload foo.data
 
   # Show a detailed status of the fleet:
-  fleet_manager status --verbose
+  main.toit --verbose status
 
-  # Uploads the file 'foo.data' to the device 'foo':
-  fleet_manager device --device=foo upload foo.data
+  # Do a soft-reset of device 'foo':
+  main.toit device --device=foo reset -m soft
 ```
 
 The help for the `reset` command looks as follows:
@@ -61,17 +63,17 @@ Global options:
 
 Examples:
   # Do a soft-reset of device 'foo':
-  fleet_manager device --device=foo reset -m soft
+  main.toit device --device=foo reset -m soft
 
   # Do a hard-reset:
-  fleet_manager device reset --mode=hard
+  main.toit device reset --mode=hard
 ```
 */
 
 main arguments:
   // Creates a root command.
   // The name of the root command is not used.
-  root-cmd := cli.Command "fleet_manager"
+  root-cmd := Command "fleet_manager"
       --help="""
         This is an imaginary fleet manager for a fleet of Toit devices.
 
@@ -86,24 +88,25 @@ main arguments:
 
 // ============= Could be in a separate file status.toit. =============
 
-create-status-command -> cli.Command:
-  return cli.Command "status"
+create-status-command -> Command:
+  return Command "status"
       --help="Shows the status of the fleet."
       --options=[
-        cli.OptionInt "max-lines" --help="Maximum number of lines to show." --default=10,
+        OptionInt "max-lines" --help="Maximum number of lines to show." --default=10,
       ]
       --examples=[
-        cli.Example "Show the status of the fleet:" --arguments="",
-        cli.Example "Show a detailed status of the fleet:" --arguments="--verbose"
+        Example "Show the status of the fleet:" --arguments="",
+        Example "Show a detailed status of the fleet:" --arguments="--verbose"
             --global-priority=7,  // Show this example for the root command.
       ]
-      --run=:: | app parsed | fleet-status app parsed
+      --run=:: fleet-status it
 
-fleet-status app/cli.Application parsed/cli.Parsed:
-  max-lines := parsed["max-lines"]
-  verbose := app.ui.level >= cli.Ui.VERBOSE-LEVEL
+fleet-status invocation/Invocation:
+  max-lines := invocation["max-lines"]
+  cli := invocation.cli
+  verbose := cli.ui.level >= Ui.VERBOSE-LEVEL
 
-  app.ui.emit
+  cli.ui.emit
       --structured=: {
           "some": "json",
           "info": "about the status",
@@ -114,8 +117,8 @@ fleet-status app/cli.Application parsed/cli.Parsed:
 
 // ============= Could be in a separate file device.toit. =============
 
-create-device-command -> cli.Command:
-  device-cmd := cli.Command "device"
+create-device-command -> Command:
+  device-cmd := Command "device"
       // Aliases can be used to invoke this command.
       --aliases=[
         "dev",
@@ -128,80 +131,84 @@ create-device-command -> cli.Command:
           last used device is used.
         """
       --options=[
-        cli.Option "device" --short-name="d"
+        Option "device" --short-name="d"
             --help="The device to operate on."
       ]
-  device-cmd.add create-reset-command
   device-cmd.add create-upload-command
+  device-cmd.add create-reset-command
   return device-cmd
 
-with-device app/cli.Application parsed/cli.Parsed [block]:
-  device := parsed["device"]
-  if not device:
-    device = app.config.get "default-device"
-
-  if not device:
-    app.ui.abort "No device specified and no default device set."
-
-  block.call device
-
-create-upload-command -> cli.Command:
-  return cli.Command "upload"
+create-upload-command -> Command:
+  return Command "upload"
       --help="""
         Uploads the given file to the device.
 
         Other useful information here.
         """
       --rest=[
-        cli.OptionString "data"
+        OptionString "data"
             --type="file"
             --help="The data to upload."
             --required,
       ]
       --examples=[
-        cli.Example
+        Example
             "Uploads the file 'foo.data' to the device 'foo':"
             --arguments="--device=foo foo.data"
             --global-priority=8,  // Include this example for super commands.
       ]
-      --run=:: | app parsed | upload-to-device app parsed
+      --run=:: upload-to-device it
 
-upload-to-device app/cli.Application parsed/cli.Parsed:
-  data := parsed["data"]
-
-  with-device app parsed: | device |
-    print "Uploading file '$data' to device '$device'."
-
-create-reset-command -> cli.Command:
-  return cli.Command "reset"
+create-reset-command -> Command:
+  return Command "reset"
       --help="""
         Resets the device.
 
         Other useful information here.
         """
       --options=[
-        cli.OptionEnum "mode" ["hard", "soft"]
+        OptionEnum "mode" ["hard", "soft"]
             --help="The reset mode to use."
             --short-name="m"
             --required,
-        cli.Flag "force" --short-name="f"
+        Flag "force" --short-name="f"
             --help="Force the reset even if the device is active.",
       ]
       --examples=[
-        cli.Example
+        Example
             "Do a soft-reset of device 'foo':"
             --arguments="--device=foo -m soft"
             --global-priority=5,  // Include this example for super commands.
-        cli.Example
+        Example
             "Do a hard-reset:"
             --arguments="--mode=hard",
       ]
-      --run=:: | app parsed | reset-device app parsed
+      --run=:: reset-device it
+
+with-device invocation/Invocation [block]:
+  cli := invocation.cli
+
+  device := invocation["device"]
+  if not device:
+    device = cli.config.get "default-device"
+
+  if not device:
+    cli.ui.abort "No device specified and no default device set."
+
+  block.call device
+
+upload-to-device invocation/Invocation:
+  data := invocation["data"]
+
+  with-device invocation: | device |
+    print "Uploading file '$data' to device '$device'."
+
+reset-device invocation/Invocation:
+  cli := invocation.cli
 
-reset-device app/cli.Application parsed/cli.Parsed:
-  mode := parsed["mode"]
-  force := parsed["force"]
+  mode := invocation["mode"]
+  force := invocation["force"]
 
-  with-device app parsed: | device |
-    app.ui.info "Resetting device '$device' in $(mode)-mode."
-    if force: app.ui.debug "Using the force if necessary."
+  with-device invocation: | device |
+    cli.ui.inform "Resetting device '$device' in $(mode)-mode."
+    if force: cli.ui.debug "Using the force if necessary."
diff --git a/examples/config.toit b/examples/config.toit
new file mode 100644
index 0000000..f88139b
--- /dev/null
+++ b/examples/config.toit
@@ -0,0 +1,35 @@
+// Copyright (C) 2024 Toitware ApS. All rights reserved.
+// Use of this source code is governed by an MIT-style license that can be
+// found in the package's LICENSE file.
+
+import cli show *
+
+config-example cli/Cli:
+  config := cli.config
+
+  print "old value: $(config.get "my-key")"
+
+  config["my-key"] = "my-value"
+  config.write
+
+dotted-example cli/Cli:
+  config := cli.config
+
+  print "old value: $(config.get "super-key.sub-key")"
+
+  config["super-key.sub-key"] = "my-value"
+  config.write
+
+main args:
+  // Uses the application name "cli-example" which will be used
+  // to compute the path of the config file.
+  root-cmd := Command "cli-example"
+      --help="""
+          An example application demonstrating configurations.
+          """
+      --run=:: run it
+  root-cmd.run args
+
+run invocation/Invocation:
+  config-example invocation.cli
+  dotted-example invocation.cli
diff --git a/examples/ui.toit b/examples/ui.toit
new file mode 100644
index 0000000..fed6d51
--- /dev/null
+++ b/examples/ui.toit
@@ -0,0 +1,70 @@
+// Copyright (C) 2024 Toitware ApS. All rights reserved.
+// Use of this source code is governed by an MIT-style license that can be
+// found in the package's LICENSE file.
+
+import cli show *
+
+some-chatty-method cli/Cli:
+  ui := cli.ui
+  ui.debug "This is a debug message."
+  ui.verbose "This is a verbose message."
+  ui.inform "This is an information message."
+  ui.warn "This is a warning message."
+  ui.error "This is an error message."
+  ui.interactive "This is an interactive message."
+  // By convention, 'result' calls should only happen in the method that
+  // initially received the Invocation object.
+  // For demonstration purposes, we call it here.
+  ui.result "This is a result message."
+
+emit-structured cli/Cli:
+  ui := cli.ui
+  ui.emit-list --kind=Ui.INFO --title="A list" [1, 2, 3]
+  ui.emit-map --kind=Ui.INFO --title="A map" {
+    "key": "value",
+    "key2": "value2",
+  }
+  ui.emit-table
+      --kind=Ui.INFO
+      --title="A table"
+      --header={"name": "Name", "age": "Age"}
+      [
+        { "name": "Alice", "age": 25 },
+        { "name": "Bob", "age": 30},
+      ]
+
+main args:
+  // Uses the application name "cli-example" which will be used
+  // to compute the path of the config file.
+  root-cmd := Command "cli-example"
+      --help="""
+          An example application demonstrating UI usage.
+
+          Run with --verbosity-level={debug, info, verbose, quiet, silent}, or
+            --output-format={text, json} to see different output.
+          Note that '--output-format=json' redirects some output to stderr.
+          """
+      --options=[
+        Flag "chatty" --help="Run the chatty method" --default=false,
+        Flag "structured" --help="Output structured data" --default=false,
+      ]
+      --run=:: run it
+  root-cmd.run args
+
+run invocation/Invocation:
+  if invocation["chatty"]:
+    some-chatty-method invocation.cli
+    return
+
+  if invocation["structured"]:
+    emit-structured invocation.cli
+    return
+
+  ui := invocation.cli.ui
+  ui.emit --kind=Ui.RESULT
+      // Block that is invoked if structured data is needed.
+      --structured=: {
+        "result": "Computed result"
+      }
+      // Block that is invoked if text data is needed.
+      --text=: "Computed result as text message."
diff --git a/main.toit b/main.toit
deleted file mode 100644
index f6d6ecb..0000000
--- a/main.toit
+++ /dev/null
@@ -1,69 +0,0 @@
-import .src.arg_parser as arguments
-
-main args:
-  command := arguments.Command "root"
-      --short_help="One-line help"
-      --aliases=["alias1", "alias2"]
-      --long_help="""
-        Some help for this command.
-        """
-      --options=[
-        arguments.Flag "xhelp" --short_name="x" --short_help="xx" --required,
-        arguments.OptionEnum "format" ["long", "short"]
-          --short_name="f"
-          --short_help="Output format"
-          --default="long",
-        arguments.Option "global" --short_help="global required flag" --required,
-      ]
-      --examples=[
-        arguments.Example "Example of subcommand"
-            --arguments="-x --format=long --global \"xxx\" other --other_int2=45 in out"
-      ]
-
-  other := arguments.Command "other"
-      --aliases=["foo", "bar"]
-      --run=:: | parsed | run_other parsed
-      --long_help="""
-        Some long help for the other command.
-
-        Multiple lines.
-        """
-      --options=[
-        arguments.Option "other" --short_help="other option",
-        arguments.OptionInt "other_int" --short_help="other int option\ntwo lines" --default=42,
-        arguments.OptionInt "other_int2" --required --multi,
-      ]
-      --rest=[
-        arguments.Option "input" --short_help="Input file" --required --type="file",
-        arguments.Option "output" --short_help="Output file" --multi --required --type="file",
-      ]
-      --examples=[
-        arguments.Example "Use a long output format"
-            --arguments="-x --format=long --global \"xxx\" --other_int2=44 in out"
-            --global_priority=3,
-      ]
-
-  other2 := arguments.Command "other2"
-      --run=:: | parsed | run_other parsed
-      --short_help="""Some short help for the other2 command.\nTwo lines."""
-      --rest=[
-        arguments.Option "input" --short_help="Input file" --required --type="file",
-        arguments.Option "output" --short_help="Output file" --multi --required --type="file",
-        arguments.Flag "flag_rest"
-      ]
-      --examples=[
-        arguments.Example "other2 example" --arguments="-x --format=long --global \"xxx\" input output output2" --global_priority=5,
-        arguments.Example "other2 example2" --arguments="--no-xhelp --global xxx x y",
-      ]
-
-  command.add other
-  command.add other2
-  command.run args
-
-run_help parsed/arguments.Parsed:
-  print "in_help"
-  print parsed
-
-run_other parsed/arguments.Parsed:
-  print "in_other"
-  print parsed
diff --git a/src/cli.toit b/src/cli.toit
index 123a6c0..f961f2d 100644
--- a/src/cli.toit
+++ b/src/cli.toit
@@ -13,11 +13,58 @@ import .help-generator_
 import .ui
 
 export Ui
+export Cache FileStore DirectoryStore
+export Config
+
+/**
+An object giving access to common operations for CLI programs.
+
+If no ui is given uses $Ui.console.
+*/
+interface Cli:
+  constructor
+      name/string
+      --ui/Ui?=null
+      --cache/Cache?=null
+      --config/Config?=null:
+    if not ui: ui = Ui.console
+    return Cli_ name --ui=ui --cache=cache --config=config
+  /**
+  The name of the application.
+
+  Used to find configurations and caches.
+  */
+  name -> string
+
+  /**
+  The UI object to use for this application.
+
+  Output should be written to this object.
+  */
+  ui -> Ui
+
+  /** The cache object for this application. */
+  cache -> Cache
+
+  /** The configuration object for this application. */
+  config -> Config
+
+  /**
+  Returns a new UI object based on the given arguments.
+
+  All non-null arguments are used to create the UI object. If an argument is null, the
+    current value is used.
+  */
+  with -> Cli
+      --name/string?=null
+      --ui/Ui?=null
+      --cache/Cache?=null
+      --config/Config?=null
 
 /**
 An object giving access to common operations for CLI programs.
 */
-class Application:
+class Cli_ implements Cli:
   /**
   The name of the application.
 
@@ -28,18 +75,38 @@ class Application:
   cache_/Cache? := null
   config_/Config? := null
 
+  /**
+  The UI object to use for this application.
+
+  Output should be written to this object.
+  */
   ui/Ui
 
-  constructor.private_ .name --.ui:
+  constructor .name --.ui --cache/Cache? --config/Config?:
+    cache_ = cache
+    config_ = config
 
+  /** The cache object for this application. */
   cache -> Cache:
     if not cache_: cache_ = Cache --app-name=name
     return cache_
 
+  /** The configuration object for this application. */
   config -> Config:
     if not config_: config_ = Config --app-name=name
     return config_
 
+  with -> Cli
+      --name/string?=null
+      --ui/Ui?=null
+      --cache/Cache?=null
+      --config/Config?=null:
+    return Cli_
+        name or this.name
+        --ui=ui or this.ui
+        --cache=cache or cache_
+        --config=config or config_
+
 /**
 A command.
 
@@ -48,7 +115,7 @@ The main program is a command, and so are all subcommands.
 class Command:
   /**
   The name of the command.
-  The name of the root command is used as application name for the $Application.
+  The name of the root command is used as application name for the $Cli.
   */
   name/string
 
@@ -105,9 +172,9 @@ class Command:
     indented lines to continue paragraphs (just like toitdoc). The first paragraph of the
     $help is used as short help, and should have meaningful content on its own.
 
-  The $run callback is invoked when the command is executed. It is given the $Application and the
-    $Parsed object. If $run is null, then at least one subcommand must be added to this
-    command.
+  The $run callback is invoked when the command is executed. It is given an
+    $Invocation object. If $run is null, then at least one subcommand must be added
+    to this command.
   */
   constructor name --usage/string?=null --help/string?=null --examples/List=[] \
       --aliases/List=[] --options/List=[] --rest/List=[] --subcommands/List=[] --hidden/bool=false \
@@ -214,26 +281,28 @@ class Command:
   Runs this command.
 
   Parses the given $arguments and then invokes the command or one of its subcommands
-    with the $Parsed output.
+    with the $Invocation output.
 
   The $invoked-command is used only for the usage message in case of an
     error. It defaults to $system.program-name.
 
-  If no UI is given, the arguments are parsed for `--verbose`, `--verbosity-level` and
-    `--output-format` to create the appropriate UI object. If a $ui is given, then these
-    arguments are ignored.
+  If no $cli is given, the arguments are parsed for `--verbose`, `--verbosity-level` and
+    `--output-format` to create the appropriate UI object. If a $cli object is given,
+    then these arguments are ignored.
 
   The $add-ui-help flag is used to determine whether to include help for `--verbose`, ...
-    in the help output. By default it is active if no $ui is provided.
+    in the help output. By default it is active if no $cli is provided.
   */
-  run arguments/List --invoked-command=system.program-name --ui/Ui?=null --add-ui-help/bool=(not ui) -> none:
-    if not ui: ui = create-ui-from-args_ arguments
-    if add-ui-help:
-      add-ui-options_
-    app := Application.private_ name --ui=ui
+  run arguments/List --invoked-command=system.program-name --cli/Cli?=null --add-ui-help/bool=(not cli) -> none:
+    if not cli:
+      ui := create-ui-from-args_ arguments
+      if add-ui-help:
+        add-ui-options_
+      cli = Cli_ name --ui=ui --cache=null --config=null
     parser := Parser_ --invoked-command=invoked-command
-    parsed := parser.parse this arguments
-    parsed.command.run-callback_.call app parsed
+    parser.parse this arguments: | path/List parameters/Parameters |
+      invocation := Invocation.private_ cli path parameters
+      invocation.command.run-callback_.call invocation
 
   add-ui-options_:
     has-output-format-option := false
@@ -361,7 +430,7 @@ class Command:
 An option to a command.
 
 Options are used for any input from the command line to the program. They must have unique names,
-  so that they can be identified in the $Parsed output.
+  so that they can be identified in the $Invocation output.
 
 Non-rest options can be used with '--$name' or '-$short-name' (if provided). Rest options are positional
   and their name is not exposed to the user except for the help.
@@ -425,7 +494,7 @@ abstract class Option:
     which is an alias for the $OptionString constructor.
 
   The $name sets the name of the option. It must be unique among all options of a command.
-    It is also used to extract the parsed value from the $Parsed object. For multi-word
+    It is also used to extract the parsed value from the $Invocation object. For multi-word
     options kebab case ('foo-bar') is recommended. The constructor automatically converts
     snake case ('foo_bar') to kebab case. This also means, that it's not possible to
     have two options that only differ in their case (kebab and snake).
@@ -878,13 +947,51 @@ The result of parsing the command line arguments.
 
 An instance of this class is given to the command's `run` method.
 */
-class Parsed:
+class Invocation:
+  /**
+  The $Cli object representing this application.
+
+  It is common to pass this object to other functions and libraries.
+  */
+  cli/Cli
+
   /**
   A list of $Command objects, representing the commands that were given on the command line.
   The first command is the root command, the last command is the command that should be executed.
   */
   path/List
 
+  /**
+  The parameters passed to the command.
+  */
+  parameters/Parameters
+
+  /**
+  Constructors a new invocation object.
+  */
+  constructor.private_ .cli .path .parameters:
+
+  /**
+  The command that should be executed.
+  */
+  command -> Command: return path.last
+
+  /**
+  Returns the value of the option with the given $name.
+  The $name must be an option of the command or one of its super commands.
+
+  If the given $name is in snake_case, it is automatically converted
+    to kebab-case.
+
+  This method is a shortcut for $parameters[name] ($Parameters.[]).
+  */
+  operator[] name/string -> any:
+    return parameters[name]
+
+/**
+The parameters passed to the command.
+*/
+class Parameters:
   /**
   The parsed options.
   All options, including flags and rest arguments, are stored in this map.
@@ -899,14 +1006,9 @@ class Parsed:
   seen-options_/Set
 
   /**
-  Builds a new $Parsed object.
+  Builds a new parameters object.
   */
-  constructor.private_ .path .options_ .seen-options_:
-
-  /**
-  The command that should be executed.
-  */
-  command -> Command: return path.last
+  constructor.private_ .options_ .seen-options_:
 
   /**
   Returns the value of the option with the given $name.
diff --git a/src/help-generator_.toit b/src/help-generator_.toit
index b39ee05..ffce3a2 100644
--- a/src/help-generator_.toit
+++ b/src/help-generator_.toit
@@ -436,24 +436,25 @@ class HelpGenerator:
     // Parse it, to verify that it actually is valid.
     // We are also using the result to reorder the options.
     parser := Parser_ --invoked-command="root" --for-help-example
-    parsed/Parsed? := null
+    invocation-path/List? := null
+    invocation-parameters/Parameters? := null
     exception := catch:
-      parsed = parser.parse example-path.first command-line
+      parser.parse example-path.first command-line: | path parameters |
+        invocation-path = path
+        invocation-parameters = parameters
     if exception:
       throw "Error in example '$arguments-line': $exception"
 
-    parsed-path := parsed.path
-
     // For each command, collect the options that are defined on it and that were
     // used in the example.
     option-to-command := {:}  // Map from option to command.
     command-level := {:}
     flags := {}
-    for j := 0; j < parsed-path.size; j++:
-      current-command/Command := parsed-path[j]
+    for j := 0; j < invocation-path.size; j++:
+      current-command/Command := invocation-path[j]
       command-level[current-command] = j
       current-command.options_.do: | option/Option |
-        if not parsed.was-provided option.name: continue.do
+        if not invocation-parameters.was-provided option.name: continue.do
         option-to-command["--$option.name"] = current-command
         if option.short-name: option-to-command["-$option.short-name"] = current-command
         if option.is-flag:
@@ -470,7 +471,7 @@ class HelpGenerator:
       if argument == "--":
         break
       if not argument.starts-with "-":
-        if path-index >= parsed-path.size - 1:
+        if path-index >= invocation-path.size - 1:
           argument-index--
           break
         else:
@@ -517,7 +518,7 @@ class HelpGenerator:
             list.add command-line[argument-index++]
           list
 
-    options-for-command.update parsed-path.last --init=(: []) : | list/List |
+    options-for-command.update invocation-path.last --init=(: []) : | list/List |
       list.add-all command-line[argument-index..]
       list
 
@@ -528,7 +529,7 @@ class HelpGenerator:
     // For examples, we don't want the full path that was used to invoke the
     // command (like `build/bin/artemis`), but only the basename.
     app-name := basename_ invoked-command_
-    parsed-path.do: | current-command |
+    invocation-path.do: | current-command |
       if is-root:
         is-root = false
         full-command.add app-name
diff --git a/src/parser_.toit b/src/parser_.toit
index ae4625f..6441323 100644
--- a/src/parser_.toit
+++ b/src/parser_.toit
@@ -42,7 +42,15 @@ class Parser_:
     ui.abort
     unreachable
 
-  parse root-command/Command arguments -> Parsed:
+  /**
+  Parses the command line $arguments and calls the given $block with
+    the result.
+
+  Calls the $block with two arguments:
+  - The path (a list of $Command) to the command that was invoked.
+  - The $Parameters that were parsed.
+  */
+  parse root-command/Command arguments/List [block] -> none:
     path := []
     // Populate the options from the default values or empty lists (for multi-options)
     options := {:}
@@ -64,10 +72,11 @@ class Parser_:
 
       seen-options.add option.name
 
-    create-help := : | arguments/List |
-      help-command := Command "help" --run=:: | app/Application _ |
-        help-command_ path arguments --invoked-command=invoked-command_ --ui=app.ui
-      Parsed.private_ [help-command] {:} {}
+    return-help := : | arguments/List |
+      help-command := Command "help" --run=:: | app/Invocation |
+        help-command_ path arguments --invoked-command=invoked-command_ --ui=app.cli.ui
+      block.call [help-command] (Parameters.private_ {:} {})
+      return
 
     command/Command? := null
     set-command := : | new-command/Command |
@@ -112,7 +121,7 @@ class Parser_:
 
         option := all-named-options.get kebab-name
         if not option:
-          if name == "help" and not is-inverted: return create-help.call []
+          if name == "help" and not is-inverted: return-help.call []
           fatal path "Unknown option: --$name"
 
         if option.is-flag and value != null:
@@ -146,7 +155,7 @@ class Parser_:
             option-length++
 
           if not option:
-            if short-name == "h": return create-help.call []
+            if short-name == "h": return-help.call []
             fatal path "Unknown option: -$short-name"
 
           i += option-length
@@ -168,7 +177,7 @@ class Parser_:
         if not subcommand:
           if argument == "help" and command == root-command:
             // Special case for the help command.
-            return create-help.call arguments[index..]
+            return-help.call arguments[index..]
 
           fatal path "Unknown command: $argument"
         set-command.call subcommand
@@ -198,4 +207,4 @@ class Parser_:
     if not command.run-callback_:
       fatal path "Missing subcommand."
 
-    return Parsed.private_ path options seen-options
+    block.call path (Parameters.private_ options seen-options)
diff --git a/src/ui.toit b/src/ui.toit
index e6e50ce..ea2ed53 100644
--- a/src/ui.toit
+++ b/src/ui.toit
@@ -118,6 +118,9 @@ abstract class PrinterBase implements Printer:
 
   emit-list --kind/int list/List --title/string?:
     indentation := print-prefix_ --kind=kind --title=title
+    emit-list_ list --indentation=indentation
+
+  emit-list_ list/List --indentation/string:
     list.do:
       // TODO(florian): should the entries be recursively pretty-printed?
       print_ "$indentation$it"
@@ -131,6 +134,9 @@ abstract class PrinterBase implements Printer:
       if value is Map:
         print_ "$indentation$key:"
         emit-map_ value --indentation="$indentation  "
+      else if value is List:
+        print_ "$indentation$key:"
+        emit-list_ value --indentation="$indentation  "
       else:
         // TODO(florian): should the entries handle lists as well.
         print_ "$indentation$key: $value"
@@ -203,6 +209,9 @@ class Ui:
   constructor.json --level/int=NORMAL-LEVEL:
     return Ui --level=level --printer=JsonPrinter
 
+  constructor.from-args args/List:
+    return create-ui-from-args_ args
+
   /**
   Emits the given $object using the $INFO kind.
 
@@ -210,23 +219,27 @@ class Ui:
     As such, the object must be a valid JSON object.
   Otherwise, the $object is converted to a string.
   */
-  info object/any:
+  inform object/any:
     emit --kind=INFO --structured=: object
 
-  /** Alias for $info. */
+  /** Alias for $inform. */
   print object/any:
-    info object
+    inform object
 
-  /** Variant of $info using the $DEBUG kind. */
+  /** Variant of $inform using the $DEBUG kind. */
   debug object/any:
     emit --kind=DEBUG --structured=: "$object"
 
-  /** Variant of $info using the $VERBOSE kind. */
+  /** Variant of $inform using the $VERBOSE kind. */
   verbose object/any:
     emit --kind=VERBOSE --structured=: "$object"
 
+  /** Variant of $verbose that only calls the block when necessary. */
+  verbose [generator]:
+    do_ --kind=VERBOSE generator
+
   /** Emits the given $object at a warning-level as a string. */
-  warning object/any:
+  warn object/any:
     emit --kind=WARNING --structured=: "$object"
 
   /** Emits the given $object at an interactive-level as a string. */
@@ -315,14 +328,17 @@ class Ui:
     passes the result to the printer.
 
   If the printer does not request a structured representation calls the $text block and
-    passes the result as string to the printer.
+    passes the result as string to the printer. The $text block may return
+    null to indicate that no output should be generated.
   */
   emit --kind/int=RESULT [--structured] [--text]:
     do_ --kind=kind:
       if printer_.needs-structured --kind=kind:
         printer_.emit-structured --kind=kind structured.call
       else:
-        printer_.emit --kind=kind "$text.call"
+        message := text.call
+        if message:
+          printer_.emit --kind=kind "$text.call"
 
   /**
   Variant of $(emit --kind [--structured] [--text]).
@@ -337,6 +353,12 @@ class Ui:
       else:
         printer_.emit --kind=kind "$(structured.call)"
 
+  /**
+  Whether the UI wants a structured representation for the given $kind.
+  */
+  wants-structured --kind/int=RESULT -> bool:
+    return printer_.needs-structured --kind=kind
+
   /**
   Aborts the program with the given error message.
 
@@ -347,6 +369,20 @@ class Ui:
   abort -> none:
     exit 1
 
+  /**
+  Returns a new Ui object with the given $level and $printer.
+
+  If $level is not provided, the level of the new Ui object is the same as
+    this object.
+
+  If $printer is not provided, the printer of the new Ui object
+    is the same as this object.
+  */
+  with --level/int?=null --printer/Printer?=null -> Ui:
+    return Ui
+        --level=level or this.level
+        --printer=printer or this.printer_
+
 /**
 Prints the given $str using $print.
 
diff --git a/tests/check_test.toit b/tests/check_test.toit
index 57e90a7..0774cb5 100644
--- a/tests/check_test.toit
+++ b/tests/check_test.toit
@@ -242,7 +242,7 @@ snake-kebab:
         cli.Option "foo-bar",
         cli.Option "foo_bar"
       ]
-      --run=:: | parsed/cli.Parsed |
+      --run=:: | parsed/cli.Invocation |
         unreachable
   expect-throw "Ambiguous option of 'root': --foo-bar.":
     root.check --invoked-command="root"
diff --git a/tests/dashdash_test.toit b/tests/dashdash_test.toit
index 605cabf..b6a2813 100644
--- a/tests/dashdash_test.toit
+++ b/tests/dashdash_test.toit
@@ -11,11 +11,11 @@ main:
       cli.Option "first" --required,
       cli.Option "arg" --multi
     ]
-    --run=:: | _ parsed| test-dashdash parsed
+    --run=:: test-dashdash it
   root.run ["--", "prog", "arg1", "arg2", "arg3"]
 
-test-dashdash parsed/cli.Parsed:
-  first := parsed["first"]
-  rest := parsed["arg"]
+test-dashdash invocation/cli.Invocation:
+  first := invocation["first"]
+  rest := invocation["arg"]
   expect-equals "prog" first
   expect-list-equals ["arg1", "arg2", "arg3"] rest
diff --git a/tests/health/readme1.toit b/tests/health/readme1.toit
index d6852ea..9ecc9a8 100644
--- a/tests/health/readme1.toit
+++ b/tests/health/readme1.toit
@@ -2,32 +2,32 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
-import cli
+import cli show *
 
 main args/List:
-  command := cli.Command "my-app"
+  command := Command "my-app"
     --help="My app does something."
     --options=[
-      cli.Option "some-option"
+      Option "some-option"
         --help="This is an option."
         --required,
-      cli.Flag "some-flag"
+      Flag "some-flag"
         --short-name="f"
         --help="This is a flag.",
     ]
     --rest=[
-      cli.Option "rest-arg"
+      Option "rest-arg"
         --help="This is a rest argument."
         --multi,
     ]
     --examples=[
-      cli.Example "Do something with the flag:"
+      Example "Do something with the flag:"
           --arguments="--some-option=foo --no-some-flag rest1 rest1",
     ]
-    --run=:: | app/cli.Application parsed/cli.Parsed |
-      print parsed["some-option"]
-      print parsed["some-flag"]
-      print parsed["rest-arg"]  // A list.
-      app.ui.result "Computed result"
+    --run=:: | invocation/Invocation |
+      print invocation["some-option"]
+      print invocation["some-flag"]
+      print invocation["rest-arg"]  // A list.
+      invocation.cli.ui.result "Computed result"
 
   command.run args
diff --git a/tests/health/readme2.toit b/tests/health/readme2.toit
index bd95c3d..88c7afa 100644
--- a/tests/health/readme2.toit
+++ b/tests/health/readme2.toit
@@ -2,15 +2,15 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
-import cli
+import cli show *
 
 main args/List:
-  command := cli.Command "my-app"
+  command := Command "my-app"
     --help="My app does something."
 
-  sub := cli.Command "subcommand"
+  sub := Command "subcommand"
     --help="This is a subcommand."
-    --run=:: | app/cli.Application parsed/cli.Parsed |
+    --run=:: | invocation/Invocation |
       print "This is a subcommand."
   command.add sub
 
diff --git a/tests/health/readme3.toit b/tests/health/readme3.toit
index c0288bf..b530988 100644
--- a/tests/health/readme3.toit
+++ b/tests/health/readme3.toit
@@ -2,39 +2,15 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
-import cli
-import cli.cache as cli
-import host.file
+import cli show Cli FileStore
 
-store-bytes app/cli.Application:
-  cache := app.cache
+store-bytes cli/Cli:
+  cache := cli.cache
 
-  data := cache.get "my-key": | store/cli.FileStore |
+  data := cache.get "my-key": | store/FileStore |
     // Block that is called when the key is not found.
+    // The returned data is stored in the cache.
     print "Data is not cached. Computing it."
     store.save #[0x01, 0x02, 0x03]
 
   print data  // Prints #[0x01, 0x02, 0x03].
-
-store-from-file app/cli.Application:
-  cache := app.cache
-
-  data := cache.get "my-file-key": | store/cli.FileStore |
-    // Block that is called when the key is not found.
-    print "Data is not cached. Computing it."
-    store.with-tmp-directory: | tmp-dir |
-      data-path := "$tmp-dir/data.txt"
-      // Create a file with some data.
-      file.write-content --path=data-path "Hello world"
-      store.move data-path
-
-  print data  // Prints the binary representation of "Hello world".
-
-main args:
-  cmd := cli.Command "my-app"
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        print "Data is cached in $app.cache.path"
-        store-bytes app
-        store-from-file app
-
-  cmd.run args
diff --git a/tests/health/readme4.toit b/tests/health/readme4.toit
index 77d3a42..12bf0d3 100644
--- a/tests/health/readme4.toit
+++ b/tests/health/readme4.toit
@@ -2,29 +2,19 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
-import cli
-import cli.cache as cli
+import cli show Cli FileStore
 import host.file
 
-store-directory app/cli.Application:
-  cache := app.cache
+store-from-file cli/Cli:
+  cache := cli.cache
 
-  directory := cache.get-directory-path "my-dir-key": | store/cli.DirectoryStore |
+  data := cache.get "my-file-key": | store/FileStore |
     // Block that is called when the key is not found.
-    // The returned directory is stored in the cache.
-    print "Directory is not cached. Computing it."
+    print "Data is not cached. Computing it."
     store.with-tmp-directory: | tmp-dir |
-      // Create a few files with some data.
-      file.write-content --path="$tmp-dir/data1.txt" "Hello world"
-      file.write-content --path="$tmp-dir/data2.txt" "Bonjour monde"
-      store.move tmp-dir
+      data-path := "$tmp-dir/data.txt"
+      // Create a file with some data.
+      file.write-content --path=data-path "Hello world"
+      store.move data-path
 
-  print directory  // Prints the path to the directory.
-
-main args:
-  cmd := cli.Command "my-app"
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        print "Data is cached in $app.cache.path"
-        store-directory app
-
-  cmd.run args
+  print data  // Prints the binary representation of "Hello world".
diff --git a/tests/health/readme5.toit b/tests/health/readme5.toit
index fc911c0..dfe1e3f 100644
--- a/tests/health/readme5.toit
+++ b/tests/health/readme5.toit
@@ -2,30 +2,20 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
-import cli
-import cli.config as cli
-
-config-example app/cli.Application:
-  config := app.config
-
-  print "old value: $(config.get "my-key")"
-
-  config["my-key"] = "my-value"
-  config.write
-
-dotted-example app/cli.Application:
-  config := app.config
-
-  print "old value: $(config.get "super-key.sub-key")"
-
-  config["super-key.sub-key"] = "my-value"
-  config.write
-
-main args:
-  cmd := cli.Command "my-app"
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        print "Configuration is stored in $app.config.path"
-        config-example app
-        dotted-example app
-
-  cmd.run args
+import cli show Cli DirectoryStore
+import host.file
+
+store-directory cli/Cli:
+  cache := cli.cache
+
+  directory := cache.get-directory-path "my-dir-key": | store/DirectoryStore |
+    // Block that is called when the key is not found.
+    // The returned directory is stored in the cache.
+    print "Directory is not cached. Computing it."
+    store.with-tmp-directory: | tmp-dir |
+      // Create a few files with some data.
+      file.write-content --path="$tmp-dir/data1.txt" "Hello world"
+      file.write-content --path="$tmp-dir/data2.txt" "Bonjour monde"
+      store.move tmp-dir
+
+  print directory  // Prints the path to the directory.
diff --git a/tests/health/readme6.toit b/tests/health/readme6.toit
new file mode 100644
index 0000000..4e41515
--- /dev/null
+++ b/tests/health/readme6.toit
@@ -0,0 +1,13 @@
+// Copyright (C) 2024 Toitware ApS.
+// Use of this source code is governed by a Zero-Clause BSD license that can
+// be found in the tests/LICENSE file.
+
+import cli show Cli Config
+
+config-example cli/Cli:
+  config := cli.config
+
+  print "old value: $(config.get "my-key")"
+
+  config["my-key"] = "my-value"
+  config.write
diff --git a/tests/health/readme7.toit b/tests/health/readme7.toit
new file mode 100644
index 0000000..8f2aaed
--- /dev/null
+++ b/tests/health/readme7.toit
@@ -0,0 +1,13 @@
+// Copyright (C) 2024 Toitware ApS.
+// Use of this source code is governed by a Zero-Clause BSD license that can
+// be found in the tests/LICENSE file.
+
+import cli show Cli Config
+
+dotted-example cli/Cli:
+  config := cli.config
+
+  print "old value: $(config.get "super-key.sub-key")"
+
+  config["super-key.sub-key"] = "my-value"
+  config.write
diff --git a/tests/health/readme8.toit b/tests/health/readme8.toit
new file mode 100644
index 0000000..6223524
--- /dev/null
+++ b/tests/health/readme8.toit
@@ -0,0 +1,15 @@
+// Copyright (C) 2024 Toitware ApS.
+// Use of this source code is governed by a Zero-Clause BSD license that can
+// be found in the tests/LICENSE file.
+
+import cli show Cli
+
+some-chatty-method cli/Cli:
+  ui := cli.ui
+  ui.debug "This is a debug message."
+  ui.verbose "This is a verbose message."
+  ui.inform "This is an information message."
+  ui.warn "This is a warning message."
+  ui.error "This is an error message."
+  ui.interactive "This is an interactive message."
+  ui.result "This is a result message."
diff --git a/tests/health/readme9.toit b/tests/health/readme9.toit
new file mode 100644
index 0000000..c4339bb
--- /dev/null
+++ b/tests/health/readme9.toit
@@ -0,0 +1,20 @@
+// Copyright (C) 2024 Toitware ApS.
+// Use of this source code is governed by a Zero-Clause BSD license that can
+// be found in the tests/LICENSE file.
+
+import cli show *
+
+main args:
+  cmd := Command "my-app"
+    --help="My app does something."
+    --run=:: run it
+
+run invocation/Invocation:
+  ui := invocation.cli.ui
+  ui.emit
+      // Block that is invoked if structured data is needed.
+      --structured=: {
+        "result": "Computed result"
+      }
+      // Block that is invoked if text data is needed.
+      --text=: "Computed result as text message."
diff --git a/tests/help_test.toit b/tests/help_test.toit
index 0213d43..8bff2bf 100644
--- a/tests/help_test.toit
+++ b/tests/help_test.toit
@@ -19,7 +19,8 @@ main:
 
 check-output expected/string [block]:
   ui := TestUi
-  block.call ui
+  cli := cli.Cli "test" --ui=ui
+  block.call cli
   all-output := ui.messages.join "\n"
   if expected != all-output and expected.size == all-output.size:
     for i := 0; i < expected.size; i++:
@@ -70,8 +71,8 @@ test-combination:
       # Example 1:
       app --option1 foo rest
     """
-  check-output cmd-help: | ui/cli.Ui |
-    cmd.run ["--help"] --ui=ui --invoked-command="bin/app"
+  check-output cmd-help: | cli/cli.Cli |
+    cmd.run ["--help"] --cli=cli --invoked-command="bin/app"
   expect-equals cmd-help (cmd.help --invoked-command="bin/app")
 
   sub := cli.Command "sub"
@@ -118,8 +119,8 @@ test-combination:
       # Sub Example 2:
       app --option1 foo sub --option_sub1='xyz'
     """
-  check-output cmd-help: | ui/cli.Ui |
-    cmd.run ["--help"] --ui=ui --invoked-command="bin/app"
+  check-output cmd-help: | cli/cli.Cli |
+    cmd.run ["--help"] --cli=cli --invoked-command="bin/app"
 
   expect-equals cmd-help (cmd.help --invoked-command="bin/app")
 
@@ -148,8 +149,8 @@ test-combination:
       app --option1 foo sub --option_sub1='xyz'
     """
 
-  check-output sub-help: | ui/cli.Ui |
-    cmd.run ["help", "sub"] --ui=ui --invoked-command="bin/app"
+  check-output sub-help: | cli/cli.Cli |
+    cmd.run ["help", "sub"] --cli=cli --invoked-command="bin/app"
 
 test-usage:
   build-usage := : | path/List |
diff --git a/tests/parser_test.toit b/tests/parser_test.toit
index f0872be..7ecd4b4 100644
--- a/tests/parser_test.toit
+++ b/tests/parser_test.toit
@@ -7,9 +7,9 @@ import expect show *
 
 import .test-ui
 
-check-arguments expected/Map parsed/cli.Parsed:
+check-arguments expected/Map invocation/cli.Invocation:
   expected.do: | key value |
-    expect-equals value parsed[key]
+    expect-equals value invocation[key]
 
 main:
   test-options
@@ -33,8 +33,7 @@ test-options:
         cli.Option "bar" --short-name="b",
         cli.OptionInt "gee" --short-name="g",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "foo_value", "bar": "bar_value", "gee": null}
   cmd.run ["-f", "foo_value", "-b", "bar_value"]
@@ -57,8 +56,7 @@ test-options:
         cli.Flag "bar" --short-name="b",
         cli.Option "fizz" --short-name="iz" --default="default_fizz",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "default_foo", "bar": true, "fizz": "default_fizz"}
   cmd.run ["-b"]
@@ -87,8 +85,7 @@ test-options:
       --options=[
         cli.Flag "foo" --short-name="f" --default=false,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": false}
   cmd.run []
@@ -103,8 +100,7 @@ test-options:
       --options=[
         cli.Flag "foo" --short-name="f" --default=true,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": true
   }
@@ -117,8 +113,7 @@ test-multi:
         cli.Option "foo" --short-name="f" --multi,
         cli.Option "bar" --short-name="b" --multi --split-commas,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": ["foo_value"], "bar": ["bar_value"]}
   cmd.run ["-f", "foo_value", "-b", "bar_value"]
@@ -147,8 +142,7 @@ test-multi:
       --options=[
         cli.OptionInt "foo" --short-name="f" --multi --split-commas,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": [1, 2, 3]}
   cmd.run ["-f", "1", "-f", "2", "-f", "3"]
@@ -158,8 +152,7 @@ test-multi:
       --options=[
         cli.Flag "foo" --short-name="f" --multi,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": [true, true, true]}
   cmd.run ["-f", "-f", "-f"]
@@ -170,8 +163,7 @@ test-multi:
       --options=[
         cli.OptionEnum "foo" ["a", "b"] --short-name="f" --multi,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": ["a", "b", "a"]}
   cmd.run ["-f", "a", "-f", "b", "-f", "a"]
@@ -183,8 +175,7 @@ test-rest:
         cli.Option "foo",
         cli.OptionInt "bar",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "foo_value", "bar": 42}
   cmd.run ["foo_value", "42"]
@@ -200,8 +191,7 @@ test-rest:
         cli.Option "foo" --required,
         cli.OptionInt "bar" --default=42,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "foo_value", "bar": 42}
   cmd.run ["foo_value"]
@@ -209,16 +199,15 @@ test-rest:
   expected = {"foo": "foo_value", "bar": 43}
   cmd.run ["foo_value", "43"]
 
-  expect-abort "Missing required rest argument: 'foo'.": | ui/cli.Ui |
-    cmd.run [] --ui=ui
+  expect-abort "Missing required rest argument: 'foo'.": | app/cli.Cli |
+    cmd.run [] --cli=app
 
   cmd = cli.Command "test"
       --rest=[
         cli.Option "foo" --required,
         cli.Option "bar" --required --multi,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "foo_value", "bar": ["bar_value"]}
   cmd.run ["foo_value", "bar_value"]
@@ -226,13 +215,13 @@ test-rest:
   expected = {"foo": "foo_value", "bar": ["bar_value", "bar_value2"]}
   cmd.run ["foo_value", "bar_value", "bar_value2"]
 
-  expect-abort "Missing required rest argument: 'bar'.": | ui/cli.Ui |
-    cmd.run ["foo_value"] --ui=ui
+  expect-abort "Missing required rest argument: 'bar'.": | app/cli.Cli |
+    cmd.run ["foo_value"] --cli=app
 
   cmd = cli.Command "test"
       --run=:: null
-  expect-abort "Unexpected rest argument: 'baz'.": | ui/cli.Ui |
-    cmd.run ["baz"] --ui=ui
+  expect-abort "Unexpected rest argument: 'baz'.": | app/cli.Cli |
+    cmd.run ["baz"] --cli=app
 
 test-subcommands:
   expected/Map? := null
@@ -242,17 +231,14 @@ test-subcommands:
             --options=[
               cli.Option "foo" --short-name="f",
             ]
-            --run=:: | app/cli.Application parsed/cli.Parsed |
-              check-arguments expected parsed,
+            --run=:: check-arguments expected it,
         cli.Command "sub2"
             --options=[
               cli.Option "bar" --short-name="b",
             ]
-            --run=:: | app/cli.Application parsed/cli.Parsed |
-              check-arguments expected parsed,
+            --run=:: check-arguments expected it
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": "foo_value"}
   cmd.run ["sub1", "-f", "foo_value"]
@@ -270,8 +256,8 @@ test-subcommands:
 
 test-no-option:
   cmd := cli.Command "test"
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        expect-throw "No option named 'foo'": parsed["foo"]
+      --run=:: | invocation/cli.Invocation |
+        expect-throw "No option named 'foo'": invocation["foo"]
   cmd.run []
 
   cmd = cli.Command "test"
@@ -283,8 +269,8 @@ test-no-option:
             --options=[
               cli.Option "bar" --short-name="b",
             ]
-            --run=:: | app/cli.Application parsed/cli.Parsed |
-              expect-throw "No option named 'gee'": parsed["gee"],
+            --run=:: | invocation/cli.Invocation |
+              expect-throw "No option named 'gee'": invocation["gee"],
       ]
 
   cmd.run ["sub1", "-b", "bar_value"]
@@ -296,8 +282,7 @@ test-invert-flag:
       --options=[
         cli.Flag "foo" --short-name="f",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": null}
   cmd.run []
@@ -312,8 +297,7 @@ test-invert-flag:
       --options=[
         cli.Flag "foo" --short-name="f" --default=true,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: check-arguments expected it
 
   expected = {"foo": true}
   cmd.run []
@@ -326,11 +310,11 @@ test-invert-non-flag:
       --options=[
         cli.Option "foo" --short-name="f",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
+      --run=:: | invocation/cli.Invocation |
         unreachable
 
-  expect-abort "Cannot invert non-boolean flag --foo.": | ui/cli.Ui |
-    cmd.run ["--no-foo"] --ui=ui
+  expect-abort "Cannot invert non-boolean flag --foo.": | app/cli.Cli |
+    cmd.run ["--no-foo"] --cli=app
 
 test-value-for-flag:
   expected/Map? := null
@@ -338,8 +322,8 @@ test-value-for-flag:
       --options=[
         cli.Flag "foo" --short-name="f",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments expected parsed
+      --run=:: | invocation/cli.Invocation |
+        check-arguments expected invocation
 
   expected = {"foo": true}
   cmd.run ["--foo=true"]
@@ -348,22 +332,22 @@ test-value-for-flag:
   cmd.run ["--foo=false"]
 
   ["on", "off", "yes", "no"].do: | value |
-    expect-abort "Invalid value for boolean flag 'foo': '$value'. Valid values are: true, false.": | ui/cli.Ui |
-      cmd.run ["--foo=$value"] --ui=ui
+    expect-abort "Invalid value for boolean flag 'foo': '$value'. Valid values are: true, false.": | app/cli.Cli |
+      cmd.run ["--foo=$value"] --cli=app
 
 test-missing-args:
   cmd := cli.Command "test"
       --options=[
         cli.Option "foo" --short-name="f",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
+      --run=:: | invocation/cli.Invocation |
         unreachable
 
-  expect-abort "Option --foo requires an argument.": | ui/cli.Ui |
-    cmd.run ["--foo"] --ui=ui
+  expect-abort "Option --foo requires an argument.": | app/cli.Cli |
+    cmd.run ["--foo"] --cli=app
 
-  expect-abort "Option -f requires an argument.": | ui/cli.Ui |
-    cmd.run ["-f"] --ui=ui
+  expect-abort "Option -f requires an argument.": | app/cli.Cli |
+    cmd.run ["-f"] --cli=app
 
 test-missing-subcommand:
   cmd := cli.Command "test"
@@ -372,16 +356,16 @@ test-missing-subcommand:
             --run=:: unreachable
       ]
 
-  expect-abort "Missing subcommand.": | ui/cli.Ui |
-    cmd.run [] --ui=ui
+  expect-abort "Missing subcommand.": | app/cli.Cli |
+    cmd.run [] --cli=app
 
 test-dash-arg:
   cmd := cli.Command "test"
       --options=[
         cli.Option "foo" --short-name="f",
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments {"foo": "-"} parsed
+      --run=:: | invocation/cli.Invocation |
+        check-arguments {"foo": "-"} invocation
 
   cmd.run ["-f", "-"]
 
@@ -396,8 +380,8 @@ test-mixed-rest-named:
       --rest=[
         cli.Option "baz" --required,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments {"foo": "foo_value", "bar": "bar_value", "baz": "baz_value"} parsed
+      --run=:: | invocation/cli.Invocation |
+        check-arguments {"foo": "foo_value", "bar": "bar_value", "baz": "baz_value"} invocation
 
   cmd.run ["--foo", "foo_value", "--bar", "bar_value", "baz_value"]
   cmd.run ["baz_value", "--foo", "foo_value", "--bar", "bar_value"]
@@ -411,8 +395,8 @@ test-mixed-rest-named:
       --rest=[
         cli.Option "baz" --required,
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments {"foo": "foo_value", "bar": "bar_value", "baz": "--foo"} parsed
+      --run=:: | invocation/cli.Invocation |
+        check-arguments {"foo": "foo_value", "bar": "bar_value", "baz": "--foo"} invocation
 
   // Because of the '--', the rest argument is not interpreted as a named argument.
   cmd.run ["--foo", "foo_value", "--bar", "bar_value", "--", "--foo"]
@@ -423,9 +407,9 @@ test-snake-kebab:
         cli.Option "foo-bar" --short-name="f",
         cli.Option "toto_titi"
       ]
-      --run=:: | app/cli.Application parsed/cli.Parsed |
-        check-arguments {"foo-bar": "foo_value", "toto-titi": "toto_value" } parsed
-        check-arguments {"foo_bar": "foo_value", "toto_titi": "toto_value" } parsed
+      --run=:: | invocation/cli.Invocation |
+        check-arguments {"foo-bar": "foo_value", "toto-titi": "toto_value" } invocation
+        check-arguments {"foo_bar": "foo_value", "toto_titi": "toto_value" } invocation
 
   cmd.run ["--foo-bar", "foo_value", "--toto-titi", "toto_value"]
   cmd.run ["--foo_bar", "foo_value", "--toto_titi", "toto_value"]
diff --git a/tests/subcommand_test.toit.toit b/tests/subcommand_test.toit.toit
index 4bfdc5e..c7f37d4 100644
--- a/tests/subcommand_test.toit.toit
+++ b/tests/subcommand_test.toit.toit
@@ -5,7 +5,7 @@
 import cli
 import expect show *
 
-check-arguments expected/Map parsed/cli.Parsed:
+check-arguments expected/Map parsed/cli.Invocation:
   expected.do: | key value |
     expect-equals value parsed[key]
 
diff --git a/tests/test_ui.toit b/tests/test_ui.toit
index 4b5cf2c..6296fbc 100644
--- a/tests/test_ui.toit
+++ b/tests/test_ui.toit
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a Zero-Clause BSD license that can
 // be found in the tests/LICENSE file.
 
+import cli as cli
 import cli.ui as cli
 import cli.parser_ as cli-parser
 import expect show *
@@ -33,8 +34,9 @@ class TestPrinter extends cli.PrinterBase:
 
 expect-abort expected/string [block]:
   ui := TestUi
+  cli := cli.Cli "test" --ui=ui
   exception := catch:
-    block.call ui
+    block.call cli
   expect-equals "abort" exception
   all-output := ui.messages.join "\n"
   if not all-output.starts-with "Error: $expected":
diff --git a/tests/ui-test.toit b/tests/ui-test.toit
index f00ebc6..6d3bd3b 100644
--- a/tests/ui-test.toit
+++ b/tests/ui-test.toit
@@ -51,11 +51,11 @@ test-console:
   printer := TestPrinter --no-needs-structured
   ui := Ui --printer=printer
 
-  ui.info "hello"
+  ui.inform "hello"
   expect-equals "hello\n" printer.stdout
   printer.reset
 
-  ui.info ["hello", "world"]
+  ui.inform ["hello", "world"]
   expect-equals "[hello, world]\n" printer.stdout
   printer.reset
 
@@ -118,7 +118,7 @@ test-console:
   """ printer.stdout
   printer.reset
 
-  ui.info {
+  ui.inform {
     "a": "b",
     "c": "d",
   }
@@ -155,7 +155,7 @@ test-console:
   expect-equals "foo\n" printer.stdout
   printer.reset
 
-  ui.warning "foo"
+  ui.warn "foo"
   expect-equals "Warning: foo\n" printer.stdout
   printer.reset
 
@@ -175,7 +175,7 @@ test-structured:
   printer := TestPrinter --needs-structured
   ui := Ui --printer=printer
 
-  ui.info "hello"
+  ui.inform "hello"
   expect-equals ["hello"] printer.structured
   printer.reset
 
@@ -192,7 +192,7 @@ test-structured:
     "foo",
     "bar",
   ]
-  ui.info list
+  ui.inform list
   expect-equals 1 printer.structured.size
   expect-identical list printer.structured[0]
   printer.reset
@@ -217,7 +217,7 @@ test-json:
 
   // Anything that isn't a result is emitted on stderr as if it was
   // a console Ui.
-  ui.info "hello"
+  ui.inform "hello"
   expect-equals "hello\n" printer.stderr
   printer.reset
 
@@ -232,7 +232,7 @@ test-json:
   }
   expect-equals "{\"foo\":1,\"bar\":2}" printer.stdout
 
-  ui.warning "some warning"
+  ui.warn "some warning"
   expect-equals "Warning: some warning\n" printer.stderr
   printer.reset