diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,3 @@
+# Changelog for TLT
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
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+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,10 @@
+# TLT
+
+TLT is a Haskell test framework oriented towards stacked monad
+transformers.  TLT has no explicit test specifications.  Tests are run
+where declared, with results accumulated and reported at the end.
+Tests can live in an arbitrary monad transformer so long as the `TLT`
+transformer is part of the stack.  Some control of the results display
+is available.
+
+See the TLT Haddock page for instructions and examples.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/TLT.cabal b/TLT.cabal
new file mode 100644
--- /dev/null
+++ b/TLT.cabal
@@ -0,0 +1,89 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.34.4.
+--
+-- see: https://github.com/sol/hpack
+
+name:           TLT
+version:        0.1.0.0
+synopsis:       Testing in monads and transformers without explicit specs
+description:    A small unit test system oriented with an emphasis on examining intermediate results of computations in monad transformers.  The Test.TLT Haddock page is the main piece of documentation; or see also the GitHub repository <https://github.com/jphmrst/TLT/>.
+category:       Test
+homepage:       https://github.com/jphmrst/TLT#readme
+bug-reports:    https://github.com/jphmrst/TLT/issues
+author:         John Maraist
+maintainer:     haskell-tlt@maraist.org
+copyright:      2022 John Maraist
+license:        LGPL-3
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+source-repository head
+  type: git
+  location: https://github.com/jphmrst/TLT
+
+library
+  exposed-modules:
+      Test.TLT
+  other-modules:
+      Paths_TLT
+  hs-source-dirs:
+      src
+  build-depends:
+      HUnit >=1.6.2 && <1.7
+    , STMonadTrans >=0.4.6 && <0.5
+    , ansi-terminal >=0.11.1 && <0.12
+    , base (>=4.14.3 && <4.15) || (>=4.15.1 && <4.16) || (>=4.16.0 && <4.17)
+    , either >=5.0.1 && <5.1
+    , free >=5.1.7 && <5.2
+    , mtl >=2.2.2 && <2.3
+    , resourcet >=1.2.4 && <1.3
+    , symbol >=0.2.4 && <0.3
+    , transformers >=0.5.6 && <0.6
+  default-language: Haskell2010
+
+executable TLT-exe
+  main-is: Failing.hs
+  other-modules:
+      Paths_TLT
+  hs-source-dirs:
+      app
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      HUnit >=1.6.2 && <1.7
+    , STMonadTrans >=0.4.6 && <0.5
+    , TLT
+    , ansi-terminal >=0.11.1 && <0.12
+    , base (>=4.14.3 && <4.15) || (>=4.15.1 && <4.16) || (>=4.16.0 && <4.17)
+    , either >=5.0.1 && <5.1
+    , free >=5.1.7 && <5.2
+    , mtl >=2.2.2 && <2.3
+    , resourcet >=1.2.4 && <1.3
+    , symbol >=0.2.4 && <0.3
+    , transformers >=0.5.6 && <0.6
+  default-language: Haskell2010
+
+test-suite TLT-test-fail
+  type: exitcode-stdio-1.0
+  main-is: Passing.hs
+  other-modules:
+      Paths_TLT
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      HUnit >=1.6.2 && <1.7
+    , STMonadTrans >=0.4.6 && <0.5
+    , TLT
+    , ansi-terminal >=0.11.1 && <0.12
+    , base (>=4.14.3 && <4.15) || (>=4.15.1 && <4.16) || (>=4.16.0 && <4.17)
+    , either >=5.0.1 && <5.1
+    , free >=5.1.7 && <5.2
+    , mtl >=2.2.2 && <2.3
+    , resourcet >=1.2.4 && <1.3
+    , symbol >=0.2.4 && <0.3
+    , transformers >=0.5.6 && <0.6
+  default-language: Haskell2010
diff --git a/app/Failing.hs b/app/Failing.hs
new file mode 100644
--- /dev/null
+++ b/app/Failing.hs
@@ -0,0 +1,23 @@
+import Test.TLT
+
+main :: IO ()
+main = do
+  tlt test
+
+test :: Monad m => TLT m ()
+test = do
+  "True passes" ~::- True
+  "2 is 3 as single Bool" ~::- 2 == 3
+  "2 is 2 as single Bool" ~::- 2 == 2
+  inGroup "== assertions" $ do
+    inGroup "pure" $ do
+      "2 is 3 as pure assertion" ~: 2 @==- 3
+      "2 is 2 as pure assertion" ~: 2 @==- 2
+    inGroup "monadic" $ do
+      "2 is 3 as result" ~: 2 @== return 3
+      "2 is 2 as result" ~: 2 @== return 2
+  inGroup "/= pure assertions" $ do
+    "2 not 3" ~: 2 @/=- 3
+    "2 not 2" ~: 2 @/=- 2
+  "2 not 3 as result" ~: 2 @/= return 3
+  "2 not 2 as result" ~: 2 @/= return 2
diff --git a/src/Test/TLT.hs b/src/Test/TLT.hs
new file mode 100644
--- /dev/null
+++ b/src/Test/TLT.hs
@@ -0,0 +1,860 @@
+{-|
+Module      : TLT
+Description : Testing in a monad transformer layer
+Copyright   : (c) John Maraist, 2022
+License     : GPL3
+Maintainer  : haskell-tlt@maraist.org
+Stability   : experimental
+Portability : POSIX
+
+TLT is a small unit test system oriented towards examining
+intermediate results of computations in monad transformers.  It is
+intended to be lightweight for the programmer, and does not require
+tests to be specified in some sort of formal list of tests.  Rather,
+tests are simply commands in a monad stack which includes the
+transformer layer @Test.TLT@.
+
+This Haddock page is the main piece of documentation; or see also the
+GitHub repository <https://github.com/jphmrst/TLT/>.
+
+-}
+
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
+module Test.TLT (
+  -- * Overview
+
+  -- |A TLT test is a command in the `TLT` monad transformer.  There
+  -- is no separation between the specification and execution of a
+  -- test; TLT makes no record of an executable test itself, only of
+  -- its result.  So in the main instance for testing, the core `IO`
+  -- monad should be wrapped in the `TLT` transformer, and in whatever
+  -- other layers are also to be tested.
+  --
+  -- In TLT, all tests are associated with a string which names or
+  -- otherwise describes the test.  Each test is introduced with one
+  -- of the @~:@, @~::@, or @~::-@ infix operators.
+  --
+  -- The simplest tests simply look for a `True` boolean value.  These
+  -- tests are introduced with @~::@ or @~::-@.  The difference
+  -- between the two is whether the boolean value is the result of a
+  -- pure `Bool` expression, or whether it is returned as the result
+  -- of a computation.  In TLT, we distinguish between the two cases
+  -- by including a trailing hyphen @-@ to operators on pure
+  -- expressions, and omitting the hyphen from operators on monadic
+  -- arguments.  So these two tests will both pass,
+  --
+  -- > "2 is 2 as single Bool" ~::- 2 == 2
+  -- > "2 is 2 a returned Bool" ~:: return $ 2 == 2
+  --
+  -- The @~:@ operator introduces a more general form of test.  The
+  -- right-hand side of @~:@ should be an `Assertion` formed with one
+  -- of TLT's built-in assertion operators, or returned from a
+  -- package's custom assertions.  `Assertion`s can give more detailed
+  -- failure information then simple `Bool`s.
+  --
+  -- Syntactically, most assertions are infix operators which start
+  -- with a @\@@ character.  The value to the left of the operator is
+  -- the expected value, and the symbol to the right is (or returns)
+  -- the value under test.  A hyphen or @P@ suffixes assertion
+  -- operators which operate on pure values; for operators without the
+  -- trailing hyphen, the value under test should is expected to be
+  -- returned as the result of a monadic computation (as with @~::@
+  -- and @~::-@).
+  --
+  -- TLT provides these assertion operators:
+  --
+  -- +---------------------------------+---------------------------------------+
+  -- | Operator                        | Meaning                               |
+  -- +=================================+=======================================+
+  -- | @/expected/ \@== /monadic/@     | The actual result must be equal       |
+  -- +---------------------------------+ to the given expected result.         |
+  -- | @/expected/ \@==- /expr/@       |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @/unexpected/ \@\/= /monadic/@  | The actual result must differ         |
+  -- +---------------------------------+ from the given unexpected result.     |
+  -- | @/unexpected/ \@\/=- /expr/@    |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @/expected/ \@< /monadic/@      | The actual result must be greater     |
+  -- +---------------------------------+ than the given lower bound.           |
+  -- | @/expected/ \@<- /expr/@        |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @/expected/ \@> /monadic/@      | The actual result must be less        |
+  -- +---------------------------------+ than the given upper bound.           |
+  -- | @/expected/ \@>- /expr/@        |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @/expected/ \@<= /monadic/@     | The actual result must be greater     |
+  -- +---------------------------------+ than or equal to the given lower      |
+  -- | @/expected/ \@<=- /expr/@       | bound.                                |
+  -- +---------------------------------+---------------------------------------+
+  -- | @/expected/ \@>= /monadic/@     | The actual result must be less than   |
+  -- +---------------------------------+ or equal to the given upper bound.    |
+  -- | @/expected/ \@>=- /expr/@       |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @empty /monadic/@               | The actual result must be an empty    |
+  -- +---------------------------------+ `Traversable` structure.              |
+  -- | @emptyP /expr/@                 |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @nonempty /monadic/@            | The actual result must be a nonempty  |
+  -- +---------------------------------+ `Traversable` structure.              |
+  -- | @nonemptyP /expr/@              |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @nothing /monadic/@             | The actual result must be `Nothing`   |
+  -- +---------------------------------+ (in a `Maybe`-typed value)            |
+  -- | @nothingP /expr/@               |                                       |
+  -- +---------------------------------+---------------------------------------+
+  -- | @assertFailed /message/@        | Trivial assertions, intended for the  |
+  -- +---------------------------------+ less interesting branches of          |
+  -- | @assertSuccess@                 | conditional and selection expressions.|
+  -- +---------------------------------+---------------------------------------+
+  --
+  -- Note that although the assertions are in pairs of one for testing
+  -- a pure expression value, and one for testing the result returned
+  -- from a monadic computation, in all of the builtin binary
+  -- assertions the /expected/ value argument is always a pure value,
+  -- not itself monadic.
+  --
+  -- The `inGroup` function allows related tests to be reported as a
+  -- group.  The function takes two arguments, a `String` name for the
+  -- group, and the `TLT` computation housing its tests.  Groups have
+  -- impact only in terms of organizing the output you see in the
+  -- final report of tests run.
+  --
+  -- Finally, it is straightforward to write new `Assertion`s for
+  -- project-specific test criteria: they are simply functions
+  -- returning monadic values.  There are several functions in the
+  -- final section of this document which transform pure predicates
+  -- into `Assertion`s, or which transform one form of `Assertion`
+  -- into another.
+  --
+  -- The source repository for TLT lives at
+  -- <https://github.com/jphmrst/tlt>.
+
+  -- * Examples
+
+  -- |These examples are from the sample executables and test suite of
+  -- the @TLT@ package.
+
+  -- ** A simple example
+
+  -- |The tests in this example are vacuous, but they show a simple
+  -- setup with both passing and failing tests.
+  --
+  -- > main :: IO ()
+  -- > main = do
+  -- >   tlt test
+  -- >
+  -- > test :: Monad m => TLT m ()
+  -- > test = do
+  -- >   "True passes" ~::- True
+  -- >   "2 is 3 as single Bool" ~::- 2 == 3
+  -- >   "2 is 2 as single Bool" ~::- 2 == 2
+  -- >   inGroup "== assertions" $ do
+  -- >     inGroup "pure" $ do
+  -- >       "2 is 3 as pure assertion" ~: 2 @==- 3
+  -- >       "2 is 2 as pure assertion" ~: 2 @==- 2
+  -- >     inGroup "monadic" $ do
+  -- >       "2 is 3 as result" ~: 2 @== return 3
+  -- >       "2 is 2 as result" ~: 2 @== return 2
+  -- >   inGroup "/= pure assertions" $ do
+  -- >     "2 not 3" ~: 2 @/=- 3
+  -- >     "2 not 2" ~: 2 @/=- 2
+  -- >   "2 not 3 as result" ~: 2 @/= return 3
+  -- >   "2 not 2 as result" ~: 2 @/= return 2
+  --
+  -- Running these tests should give:
+  --
+  -- > Running tests:
+  -- > - 2 is 3 as single Bool: FAIL Expected True but got False
+  -- > - == assertions:
+  -- >   - pure:
+  -- >     - 2 is 3 as pure assertion: FAIL Expected 2 but got 3
+  -- >   - monadic:
+  -- >     - 2 is 3 as result: FAIL Expected 2 but got 3
+  -- > - /= pure assertions:
+  -- >   - 2 not 2: FAIL Expected other than 2 but got 2
+  -- > - 2 not 2 as result: FAIL Expected other than 2 but got 2
+  -- > Found 5 errors in 11 tests; exiting
+  --
+  -- Note that only failing tests appear.  This can be configured in the
+  -- @test@ command: add a call at the beginning of @test@ to
+  -- @reportAllTestResults@ to control this behavior:
+  --
+  -- > test :: Monad m => TLT m ()
+  -- > test = do
+  -- >   reportAllTestResults True
+  -- >   "True passes" ~::- True
+  -- >   ...
+  --
+  -- and the output will be
+  --
+  -- > Running tests:
+  -- > - True passes: Pass
+  -- > - 2 is 3 as single Bool: FAIL Expected True but got False
+  -- > - 2 is 2 as single Bool: Pass
+  -- > - == assertions:
+  -- >   - pure:
+  -- >     - 2 is 3 as pure assertion: FAIL Expected 2 but got 3
+  -- >     - 2 is 2 as pure assertion: Pass
+  -- >   - monadic:
+  -- >     - 2 is 3 as result: FAIL Expected 2 but got 3
+  -- >     - 2 is 2 as result: Pass
+  -- > - /= pure assertions:
+  -- >   - 2 not 3: Pass
+  -- >   - 2 not 2: FAIL Expected other than 2 but got 2
+  -- > - 2 not 3 as result: Pass
+  -- > - 2 not 2 as result: FAIL Expected other than 2 but got 2
+  -- > Found 5 errors in 11 tests; exiting
+
+  -- ** Testing monad transformers
+
+  -- |In the previous example `TLT` was the outermost (in fact only)
+  -- monad transformer, but it can appear at any level of the test
+  -- suite's application stack.  Using `TLT` at other than the top
+  -- level is easiest when all of the transformers which might wrap it
+  -- are declared as instances of `MonadTLT`.
+  --
+  -- Consider an application which declares two monad transformers
+  -- @M1T@ and @M2T@.  For simplicity here we take them to be just
+  -- aliases for `IdentityT`:
+  --
+  -- > newtype Monad m => M1T m a = M1T { unwrap1 :: IdentityT m a }
+  -- > runM1T :: Monad m => M1T m a -> m a
+  -- > runM1T = runIdentityT . unwrap1
+  -- >
+  -- > newtype Monad m => M2T m a = M2T { unwrap2 :: IdentityT m a }
+  -- > runM2T :: Monad m => M2T m a -> m a
+  -- > runM2T = runIdentityT . unwrap2
+  --
+  -- And we elide the usual details of including each of them in
+  -- `Functor`, `Applicative`, `Monad` and `MonadTrans`.  We can
+  -- declare instances of each in `MonadTLT`,
+  --
+  -- > instance MonadTLT m n => MonadTLT (M1T m) n where
+  -- >   liftTLT = lift . liftTLT
+  --
+  -- and similarly for @M2T@.  Note that this declaration does require
+  -- @FlexibleInstances@ (because @n@ does not appear in the instance
+  -- type), @MultiParamTypeClasses@ (because we must mention both the
+  -- top transformer @m@ and the monadic type @n@ directly wrapped by
+  -- `TLT` within @m@), and @UndecidableInstances@ (because @n@ is not
+  -- smaller in the recursive context of `MonadTLT`, which is not
+  -- actually a problem because in the definition of `MonadTLT`, @n@
+  -- is functionally dependent on @m@, which /is/ smaller in the
+  -- recursive context) in the module where the `MonadTLT` instance is
+  -- declared.
+  --
+  -- Now it is convenient to test both transformers:
+  --
+  -- > ttest = do
+  -- >   runM1T $ inGroup "M1T tests" $ m1tests
+  -- >   runM2T $ inGroup "M2T tests" $ m2tests
+  -- >
+  -- > m1tests = M1T $ do
+  -- >   "3 is 3 as pure assertion" ~: 3 @==- 3
+  -- >   "4 is 4 as pure assertion" ~: 4 @==- 4
+  -- >
+  -- > m2tests = M2T $ do
+  -- >   "5 is 5 as pure assertion" ~: 5 @==- 5
+  -- >   "6 is 6 as pure assertion" ~: 6 @==- 6
+  --
+  -- It is not necessary, for example, to harvest test declarations
+  -- from the executions of the @MnT@s for assembly into an overall
+  -- test declaration.
+
+  -- * The TLT transformer
+  TLT, tlt, MonadTLT, liftTLT,
+  -- ** Session options
+  reportAllTestResults, setExitAfterFailDisplay,
+  -- * Writing tests
+  Assertion,
+  -- ** `TLT` commands
+  (~:), (~::), (~::-), tltFail, inGroup,
+  -- ** Assertions
+  -- *** About the values of pure expressions of `Eq`- and `Ord`-type
+  (@==),  (@/=),  (@<),  (@>),  (@<=),  (@>=),
+  -- *** About monadic computations returing `Eq`s and `Ord`s
+  (@==-), (@/=-), (@<-), (@>-), (@<=-), (@>=-),
+  -- *** About list values
+  empty, nonempty, emptyP, nonemptyP,
+  -- *** About `Maybe` values
+  nothing, nothingP, assertFailed, assertSuccess,
+  -- ** Building new assertions
+  -- *** Unary assertions
+  liftAssertionPure, assertionPtoM, liftAssertionM,
+  -- *** Binary assertions
+  liftAssertion2Pure, assertion2PtoM, liftAssertion2M
+
+  ) where
+
+import Data.Maybe
+import Control.Exception
+import Control.Monad
+import Control.Monad.IO.Class
+import Control.Monad.ST.Trans
+import Control.Monad.Trans.Class
+-- import Control.Monad.Trans.Either
+import Control.Monad.Trans.Free
+import Control.Monad.Trans.Identity
+import Control.Monad.Trans.Maybe
+import Control.Monad.Trans.Reader
+import Control.Monad.Trans.Resource
+import Control.Monad.Trans.State.Strict
+import qualified Control.Monad.Trans.State.Lazy as SL
+import qualified Control.Monad.Trans.Writer.Lazy as WL
+import qualified Control.Monad.Trans.Writer.Strict as WS
+import System.Console.ANSI
+import System.Exit
+
+-- * Results of tests
+
+-- |Reasons why a test might fail.
+data TestFail = Asserted String
+                -- ^ A failure arising from an `Assertion` which is not met.
+              | Erred String
+                -- ^ A failure associated with a call to a Haskell
+                -- function triggering an error.
+
+formatFail :: TestFail -> String
+formatFail (Asserted s) = s
+formatFail (Erred s) = "Assertion raised exception: " ++ s
+
+-- |An assertion is a computation (typically in the monad wrapped by
+-- `TLT`) which returns a list of zero of more reasons for the failure
+-- of the assertion.  A successful computation returns an empty list:
+-- no reasons for failure, hence success.
+type Assertion m = m [TestFail]
+
+-- |Hierarchical structure holding the result of running tests,
+-- possibly grouped into tests.
+data TestResult = Test String [TestFail]
+                | Group String Int Int [TestResult]
+                  -- ^ The `Int`s are respectively the total number of
+                  -- tests executed, and total number of failures
+                  -- detected.
+
+-- |Return the number of failed tests reported in a `TestResult`.
+failCount :: TestResult -> Int
+failCount (Test _ []) = 0
+failCount (Test _ _) = 1
+failCount (Group _ _ n _) = n
+
+testCount :: TestResult -> Int
+testCount (Test _ _) = 1
+testCount (Group _ n _ _) = n
+
+totalFailCount :: [TestResult] -> Int
+totalFailCount = foldr (+) 0 . map failCount
+
+totalTestCount :: [TestResult] -> Int
+totalTestCount = foldr (+) 0 . map testCount
+
+-- |Report the results of tests.
+report :: TLTopts -> [TestResult] -> IO ()
+report (TLTopts showPasses exitAfterFailDisplay) trs =
+  let fails = totalFailCount trs
+      tests = totalTestCount trs
+  in do report' "" trs
+        if fails > 0
+          then do boldRed
+                  putStrLn $
+                    "Found " ++ show fails ++ " error"
+                      ++ (if fails > 1 then "s" else "")
+                      ++ " in " ++ show tests ++ " tests; exiting"
+                  mediumBlack
+                  when exitAfterFailDisplay exitFailure
+          else do boldGreen
+                  putStrLn $ show tests ++ " test"
+                    ++ (if tests > 1 then "s" else "")
+                    ++ " passing."
+                  mediumBlack
+  where report' ind trs = forM_ trs $ \ tr ->
+          when (failCount tr > 0 || showPasses) $
+            case tr of
+              Test s r -> do
+                putStr $ ind ++ "- " ++ s ++ ": "
+                case r of
+                  [] -> do
+                    greenPass
+                    putStrLn ""
+                  x : [] -> do
+                    redFail
+                    putStrLn $ " " ++ formatFail x
+                  _ -> do
+                    redFail
+                    putStrLn ":"
+                    forM_ r $ \ f -> putStrLn $ ind ++ "- " ++ formatFail f
+              Group s _ _ trs' -> do
+                putStrLn $ ind ++ "- " ++ s ++ ":"
+                report' ("  " ++ ind) trs'
+
+boldBlack = setSGR [
+  SetColor Foreground Vivid Black, SetConsoleIntensity BoldIntensity ]
+boldRed = setSGR [
+  SetColor Foreground Vivid Red, SetConsoleIntensity BoldIntensity ]
+boldGreen = setSGR [
+  SetColor Foreground Vivid Green, SetConsoleIntensity BoldIntensity ]
+
+mediumRed = setSGR [
+  SetColor Foreground Vivid Red, SetConsoleIntensity NormalIntensity ]
+mediumGreen = setSGR [
+  SetColor Foreground Vivid Green, SetConsoleIntensity NormalIntensity ]
+mediumBlue = setSGR [
+  SetColor Foreground Vivid Blue, SetConsoleIntensity NormalIntensity ]
+mediumBlack = setSGR [
+  SetColor Foreground Vivid Black, SetConsoleIntensity NormalIntensity ]
+
+greenPass = do
+  mediumBlue
+  putStr "Pass"
+  mediumBlack
+
+redFail = do
+  boldRed
+  putStr "FAIL"
+  mediumBlack
+
+-- |Accumulator for test results, in the style of a simplified Huet's
+-- zipper which only ever adds to the end of the structure.
+data TRBuf = Buf TRBuf Int Int String [TestResult] | Top Int Int [TestResult]
+
+-- |Add a single test result to a `TRBuf`.
+addResult :: TRBuf -> TestResult -> TRBuf
+addResult (Top tc fc trs) tr =
+  Top (tc + testCount tr) (fc + failCount tr) $ tr : trs
+addResult (Buf up tc fc s trs) tr =
+  Buf up (tc + testCount tr) (fc + failCount tr) s $ tr : trs
+
+-- |Convert the topmost group of a bottom-up `TRBuf` into a completed
+-- top-down report about the group.
+currentGroup :: TRBuf -> TestResult
+currentGroup (Buf up tc fc s trs) = Group s tc fc (reverse trs)
+
+-- |Derive a new `TRBuf` corresponding to finishing the current group
+-- and continuing to accumulate results into its enclosure.
+popGroup :: TRBuf -> TRBuf
+popGroup trb@(Buf acc _ _ _ _) = addResult acc $ currentGroup trb
+
+-- |Convert a `TRBuf` into a list of top-down `TestResult`s.
+closeTRBuf :: TRBuf -> [TestResult]
+closeTRBuf (Top _ _ ts) = reverse ts
+closeTRBuf b = closeTRBuf $ popGroup b
+
+-- |Record of options which may be specified for running and reporting
+-- TLT tests.
+data TLTopts = TLTopts {
+  optShowPasses :: Bool,
+  optQuitAfterFailReport :: Bool
+}
+
+-- |Default initial options
+defaultOpts = TLTopts False True
+
+-- |Update the display of showing passes in a `TLTopts` record.
+withShowPasses :: TLTopts -> Bool -> TLTopts
+withShowPasses (TLTopts _ f) b = TLTopts b f
+
+-- |Update the display of showing passes in a `TLTopts` record.
+withExitAfterFail :: TLTopts -> Bool -> TLTopts
+withExitAfterFail (TLTopts p _) b = TLTopts p b
+
+-- |Synonym for the elements of the `TLT` state.
+type TLTstate = (TLTopts, TRBuf)
+
+-- |Monad transformer for TLT tests.  This layer stores the results
+-- from tests as they are executed.
+newtype Monad m => TLT m r = TLT { unwrap :: StateT TLTstate m r }
+  deriving (Functor, Applicative, Monad, MonadTrans, MonadIO)
+
+{- ------------------------------------------------------------ -}
+
+-- |Extending `TLT` operations across other monad transformers.  For
+-- easiest and most flexible testing, declare the monad transformers
+-- of your application as instances of this class.
+class (Monad m, Monad n) => MonadTLT m n | m -> n where
+  -- |Lift TLT operations within a monad transformer stack.  Note that
+  -- with enough transformer types included in this class, the
+  -- @liftTLT@ function should usually be unnecessary: the commands in
+  -- this module which actually configure testing, or specify a test,
+  -- already @liftTLT@ their own result.  So they will all act as
+  -- top-level transformers in @MonadTLT@.
+  liftTLT :: TLT n a -> m a
+
+instance Monad m => MonadTLT (TLT m) m where
+  liftTLT = id
+
+instance (MonadTLT m n, Functor f) => MonadTLT (FreeT f m) n where
+    liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (IdentityT m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (MaybeT m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (ReaderT r m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (ResourceT m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (StateT s m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (SL.StateT s m) n where
+  liftTLT = lift . liftTLT
+
+instance MonadTLT m n => MonadTLT (STT s m) n where
+  liftTLT = lift . liftTLT
+
+instance (MonadTLT m n, Monoid w) => MonadTLT (WL.WriterT w m) n where
+  liftTLT = lift . liftTLT
+
+instance (MonadTLT m n, Monoid w) => MonadTLT (WS.WriterT w m) n where
+  liftTLT = lift . liftTLT
+
+{- ------------------------------------------------------------ -}
+
+-- |Execute the tests specified in a `TLT` monad, and report the
+-- results.
+tlt :: MonadIO m => TLT m r -> m ()
+tlt (TLT t) = do
+  liftIO $ putStrLn "Running tests:"
+  (_, (opts, resultsBuf)) <- runStateT t $ (defaultOpts, Top 0 0 [])
+  liftIO $ report opts $ closeTRBuf resultsBuf
+
+-- |This function controls whether `tlt` will report only tests which
+-- fail, suppressing any display of tests which pass, or else report
+-- the results of all tests.  The default is the former: the idea is
+-- that no news should be good news, with the programmer bothered only
+-- with problems which need fixing.
+reportAllTestResults :: MonadTLT m n => Bool -> m ()
+reportAllTestResults b = liftTLT $ TLT $ do
+  (opts, tr) <- get
+  put $ (opts `withShowPasses` b, tr)
+
+-- |This function controls whether `tlt` will exit after displaying
+-- test results which include at least one failing test.  By default,
+-- it will exit in this situation.  The idea is that a test suite can
+-- be broken into parts when it makes sense to run the latter parts
+-- only when the former parts all pass.
+setExitAfterFailDisplay :: MonadTLT m n => Bool -> m ()
+setExitAfterFailDisplay b = liftTLT $ TLT $ do
+  (opts, tr) <- get
+  put $ (opts `withExitAfterFail` b, tr)
+
+-- |Report a failure.  Useful in pattern-matching cases which are
+-- entirely not expected.
+tltFail :: MonadTLT m n => String -> String -> m ()
+desc `tltFail` detail = liftTLT $ TLT $ do
+  (opts, before) <- get
+  let after = addResult before $ Test desc [Asserted detail]
+  put (opts, after)
+
+-- |Organize the tests in the given subcomputation as a separate group
+-- within the test results we will report.
+inGroup :: MonadTLT m n => String -> m a -> m a
+inGroup name group = do
+  (opts, before) <- liftTLT $ TLT get
+  liftTLT $ TLT $ put $ (opts, Buf before 0 0 name [])
+  result <- group
+  (opts', after) <- liftTLT $ TLT $ get
+  liftTLT $ TLT $ put $ (opts', popGroup after)
+  return result
+
+-- * Specifying individual tests
+
+infix 0 ~:, ~::, ~::-
+
+-- |Label and perform a test of an `Assertion`.
+--
+-- ===== Example
+--
+-- > test :: Monad m => TLT m ()
+-- > test = do
+-- >   "2 is 2 as result" ~: 2 @== return 2    -- This test passes.
+-- >   "2 not 3" ~: 2 @/=- 3                   -- This test fails.
+(~:) :: MonadTLT m n => String -> Assertion m -> m ()
+s ~: a = do
+  (opts, oldState) <- liftTLT $ TLT $ get
+  assessment <- a
+  liftTLT $ TLT $ put (opts, addResult oldState $ Test s assessment)
+
+-- |Label and perform a test of a (pure) boolean value.
+--
+-- ===== Example
+--
+-- > test :: Monad m => TLT m ()
+-- > test = do
+-- >   "True passes" ~::- return True                 -- This test passes.
+-- >   "2 is 2 as single Bool" ~::- return (2 == 2)   -- This test passes.
+-- >   "2 is 3!?" ~::- myFn 4 "Hammer"                -- Passes if myFn (which
+-- >                                                  -- must be monadic)
+-- >                                                  -- returns True.
+(~::-) :: MonadTLT m n => String -> Bool -> m ()
+s ~::- b = do
+  (opts, oldState) <- liftTLT $ TLT $ get
+  liftTLT $ TLT $ put (opts, addResult oldState $ Test s $
+        if b then [] else [Asserted $ "Expected True but got False"])
+
+-- |Label and perform a test of a boolean value returned by a
+-- computation in the wrapped monad @m@.
+--
+-- ===== Example
+--
+-- > test :: Monad m => TLT m ()
+-- > test = do
+-- >   "True passes" ~::- True               -- This test passes.
+-- >   "2 is 2 as single Bool" ~::- 2 == 2   -- This test passes.
+-- >   "2 is 3!?" ~::- 2 == 2                -- This test fails.
+(~::) :: MonadTLT m n => String -> m Bool -> m ()
+s ~:: bM = do
+  b <- bM
+  (opts, oldState) <- liftTLT $ TLT $ get
+  liftTLT $ TLT $ put (opts, addResult oldState $ Test s $
+        if b then [] else [Asserted $ "Expected True but got False"])
+
+infix 1 @==,  @/=,  @<,  @>,  @<=,  @>=
+infix 1 @==-, @/=-, @<-, @>-, @<=-, @>=-
+
+-- |Transform a binary function on an expected and an actual value
+-- (plus a binary generator of a failure message) into an `Assertion`
+-- for a pure given actual value.
+--
+-- ===== Example
+--
+-- TLT's scalar-testing operators like @\@==-@ are defined with this
+-- function:
+--
+-- > (@==-) :: (Monad m, Eq a, Show a) => a -> a -> Assertion m
+-- > (@==-) = liftAssertion2Pure (==) $
+-- >   \ exp actual -> "Expected " ++ show exp ++ " but got " ++ show actual
+--
+-- The `(==)` operator tests equality, and the result here allows the
+-- assertion that a value should be exactly equal to a target.  The
+-- second argument formats the detail reported when the assertion
+-- fails.
+liftAssertion2Pure ::
+  (Monad m) => (a -> a -> Bool) -> (a -> a -> String) -> a -> a -> Assertion m
+liftAssertion2Pure tester explainer exp actual = return $
+  if (tester exp actual) then [] else [Asserted $ explainer exp actual]
+
+-- |Given an `Assertion` for two pure values (expected and actual),
+-- lift it to an `Assertion` expecting the actual value to be returned
+-- from a computation.
+--
+-- ===== Examples
+--
+-- The TLT assertion `(@==)` lifts `(@==-)` from expecting a pure
+-- actual result to expecting a computation returning a value to test.
+--
+-- > (@==) :: (Monad m, Eq a, Show a) => a -> m a -> Assertion m
+-- > (@==) = assertion2PtoM (@==-)
+assertion2PtoM ::
+  (Monad m) => (a -> a -> Assertion m) -> a -> m a -> Assertion m
+assertion2PtoM pa exp actualM = do actual <- actualM
+                                   pa exp actual
+
+-- |Transform a binary function on expected and actual values (plus
+-- a generator of a failure message) into an `Assertion` where the
+-- actual value is to be returned from a subcomputation.
+liftAssertion2M ::
+  (Monad m) => (a -> a -> Bool) -> (a -> a -> String) -> a -> m a -> Assertion m
+liftAssertion2M tester explainer exp actualM =
+  let assertPure = liftAssertion2Pure tester explainer exp
+  in do actual <- actualM
+        assertPure actual
+
+-- |Assert that two values are equal.  This assertion takes an
+-- expected and an actual /value/; see `(@==)` to compare the result
+-- of a /monadic computation/ to an expected value.
+--
+-- ===== Examples
+--
+-- > test :: Monad m => TLT m ()
+-- > test = do
+-- >   "Make sure that 2 is still equal to itself" ~: 2 @==- 2
+-- >   "Make sure that there are four lights" ~: 4 @==- length lights
+(@==-) :: (Monad m, Eq a, Show a) => a -> a -> Assertion m
+(@==-) = liftAssertion2Pure (==) $
+  \ exp actual -> "Expected " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a calculated value is as expected.  This assertion
+-- compare the result of a /monadic computation/ to an expected value;
+-- see `(@==-)` to compare an /actual value/ to the expected value.
+--
+-- ===== Examples
+--
+-- > test :: Monad m => TLT m ()
+-- > test = do
+-- >   "Make sure that 2 is still equal to itself" ~: 2 @== return 2
+-- >   "Make sure that there are four lights" ~: 4 @== countLights
+-- >                                             -- where countLights :: m Int
+(@==) :: (Monad m, Eq a, Show a) => a -> m a -> Assertion m
+(@==) = assertion2PtoM (@==-)
+
+-- |Assert that two values are not equal.  This assertion takes an
+-- expected and an actual /value/; see `(@/=)` to compare the result
+-- of a /monadic computation/ to an expected value.
+(@/=-) :: (Monad m, Eq a, Show a) => a -> a -> Assertion m
+(@/=-) = liftAssertion2Pure (/=) $
+  \ exp actual ->
+    "Expected other than " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a calculated value differs from some known value.
+-- This assertion compares the result of a /monadic computation/ to an
+-- expected value; see `(@/=-)` to compare an /actual value/ to the
+-- expected value.
+(@/=) :: (Monad m, Eq a, Show a) => a -> m a -> Assertion m
+(@/=) = assertion2PtoM (@/=-)
+
+-- |Assert that a given boundary is strictly less than some value.
+-- This assertion takes an expected and an actual /value/; see `(@<)`
+-- to compare the result of a /monadic computation/ to an expected
+-- value.
+(@<-) :: (Monad m, Ord a, Show a) => a -> a -> Assertion m
+(@<-) = liftAssertion2Pure (<) $
+  \ exp actual ->
+    "Lower bound (open) is " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a given, constant boundary is strictly less than some
+-- calculated value.  This assertion compares the result of a /monadic
+-- computation/ to an expected value; see `(@<-)` to compare an
+-- /actual value/ to the expected value.
+(@<) :: (Monad m, Ord a, Show a) => a -> m a -> Assertion m
+(@<) = assertion2PtoM (@<-)
+
+-- |Assert that a given boundary is strictly less than some value.
+-- This assertion takes an expected and an actual /value/; see `(@>)`
+-- to compare the result of a /monadic computation/ to an expected
+-- value.
+(@>-) :: (Monad m, Ord a, Show a) => a -> a -> Assertion m
+(@>-) = liftAssertion2Pure (>) $
+  \ exp actual ->
+    "Upper bound (open) is " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a given, constant boundary is strictly less than some
+-- calculated value.  This assertion compares the result of a /monadic
+-- computation/ to an expected value; see `(@>-)` to compare an
+-- /actual value/ to the expected value.
+(@>) :: (Monad m, Ord a, Show a) => a -> m a -> Assertion m
+(@>) = assertion2PtoM (@>-)
+
+-- |Assert that a given boundary is strictly less than some value.
+-- This assertion takes an expected and an actual /value/; see `(@<=)`
+-- to compare the result of a /monadic computation/ to an expected
+-- value.
+(@<=-) :: (Monad m, Ord a, Show a) => a -> a -> Assertion m
+(@<=-) = liftAssertion2Pure (<=) $
+  \ exp actual ->
+    "Lower bound (closed) is " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a given, constant boundary is strictly less than some
+-- calculated value.  This assertion compares the result of a /monadic
+-- computation/ to an expected value; see `(@<=-)` to compare an
+-- /actual value/ to the expected value.
+(@<=) :: (Monad m, Ord a, Show a) => a -> m a -> Assertion m
+(@<=) = assertion2PtoM (@<=-)
+
+-- |Assert that a given boundary is strictly less than some value.
+-- This assertion takes an expected and an actual /value/; see `(@>=)`
+-- to compare the result of a /monadic computation/ to an expected
+-- value.
+(@>=-) :: (Monad m, Ord a, Show a) => a -> a -> Assertion m
+(@>=-) = liftAssertion2Pure (>=) $
+  \ exp actual ->
+    "Upper bound (closed) is " ++ show exp ++ " but got " ++ show actual
+
+-- |Assert that a given, constant boundary is strictly less than some
+-- calculated value.  This assertion compares the result of a /monadic
+-- computation/ to an expected value; see `(@>=-)` to compare an
+-- /actual value/ to the expected value.
+(@>=) :: (Monad m, Ord a, Show a) => a -> m a -> Assertion m
+(@>=) = assertion2PtoM (@>=-)
+
+-- |This assertion always fails with the given message.
+assertFailed :: Monad m => String -> Assertion m
+assertFailed msg = return [Asserted msg]
+
+-- |This assertion always succeeds.
+assertSuccess :: Monad m => Assertion m
+assertSuccess = return []
+
+-- |Transform a unary function on a value (plus a generator of a
+-- failure message) into a unary function returning an `Assertion` for
+-- a pure given actual value.
+--
+-- ===== Example
+--
+-- The TLT assertion `emptyP` is built from the `Traversable` predicate
+-- `null`
+--
+-- > emptyP :: (Monad m, Traversable t) => t a -> Assertion m
+-- > emptyP = liftAssertionPure null
+-- >            (\ _ -> "Expected empty structure but got non-empty")
+
+liftAssertionPure ::
+  (Monad m) => (a -> Bool) -> (a -> String) -> a -> Assertion m
+liftAssertionPure tester explainer actual = return $
+  if (tester actual) then [] else [Asserted $ explainer actual]
+
+-- |Given an `Assertion` for a pure (actual) value, lift it to an
+-- `Assertion` expecting the value to be returned from a computation.
+--
+-- ===== Example
+--
+-- The TLT assertion `empty` on monadic computations returning lists
+-- is defined in terms of the corresponging assertion on pure
+-- list-valued expressions.
+--
+-- > empty :: (Monad m, Traversable t) => m (t a) -> Assertion m
+-- > empty = assertionPtoM emptyP
+assertionPtoM :: (Monad m) => (a -> Assertion m) -> m a -> Assertion m
+assertionPtoM pa actualM = do actual <- actualM
+                              pa actual
+
+-- |Transform a unary function on an actual value (plus a generator of
+-- a failure message) into an `Assertion` where the value is to be
+-- returned from a subcomputation.
+liftAssertionM ::
+  (Monad m) => (a -> Bool) -> (a -> String) -> m a -> Assertion m
+liftAssertionM tester explainer actualM =
+  let assertPure = liftAssertionPure tester explainer
+  in do actual <- actualM
+        assertPure actual
+
+-- |Assert that a pure traversable structure (such as a list) is
+-- empty.
+emptyP :: (Monad m, Traversable t) => t a -> Assertion m
+emptyP = liftAssertionPure null
+           (\ _ -> "Expected empty structure but got non-empty")
+
+-- |Assert that a traversable structure (such as a list) returned from
+-- a computation is empty.
+empty :: (Monad m, Traversable t) => m (t a) -> Assertion m
+empty = assertionPtoM emptyP
+
+-- |Assert that a pure traversable structure (such as a list) is
+-- nonempty.
+nonemptyP :: (Monad m, Traversable t) => t a -> Assertion m
+nonemptyP = liftAssertionPure (not . null)
+              (\ _ -> "Expected non-empty structure but got empty")
+
+-- |Assert that a traversable structure (such as a list) returned from
+-- a computation is non-empty.
+nonempty :: (Monad m, Traversable t) => m (t a) -> Assertion m
+nonempty = assertionPtoM nonemptyP
+
+-- |Assert that a `Maybe` value is `Nothing`.
+nothingP :: Monad m => Maybe a -> Assertion m
+nothingP = liftAssertionPure isNothing
+           (\ _ -> "Expected empty Maybe value but got non-Nothing")
+
+-- |Assert that a `Maybe` result ofa computation is `Nothing`.
+nothing :: Monad m => m (Maybe a) -> Assertion m
+nothing = assertionPtoM nothingP
diff --git a/test/Passing.hs b/test/Passing.hs
new file mode 100644
--- /dev/null
+++ b/test/Passing.hs
@@ -0,0 +1,84 @@
+
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+import Test.TLT
+import Control.Monad.Trans.Identity
+import Control.Monad.Trans
+
+main :: IO ()
+main = do
+  tlt test
+  tlt ttest
+
+test :: Monad m => TLT m ()
+test = do
+  "True passes" ~::- True
+  "2 is 2 as single Bool" ~::- 2 == 2
+  inGroup "== assertions" $ do
+    inGroup "pure" $ do
+      "2 is 2 as pure assertion" ~: 2 @==- 2
+    inGroup "monadic" $ do
+      "2 is 2 as result" ~: 2 @== return 2
+  inGroup "/= pure assertions" $ do
+    "2 not 3" ~: 2 @/=- 3
+    "2 not 4" ~: 2 @/=- 4
+  "2 not 3 as result" ~: 2 @/= return 3
+
+newtype Monad m => M1T m a = M1T { unwrap1 :: IdentityT m a }
+runM1T :: Monad m => M1T m a -> m a
+runM1T = runIdentityT . unwrap1
+newtype Monad m => M2T m a = M2T { unwrap2 :: IdentityT m a }
+runM2T :: Monad m => M2T m a -> m a
+runM2T = runIdentityT . unwrap2
+
+instance Monad m => Functor (M1T m) where
+  fmap f (M1T m) = M1T $ do
+    v <- m
+    return $ f v
+instance Monad m => Applicative (M1T m) where
+  pure v = M1T $ pure v
+  (M1T m1) <*> (M1T m2) = M1T $ do
+    f <- m1
+    v <- m2
+    return (f v)
+instance Monad m => Monad (M1T m) where
+  (M1T m) >>= f = M1T $ m >>= (unwrap1 . f)
+  (M1T m1) >> (M1T m2) = M1T $ m1 >> m2
+  return v = M1T $ return v
+instance MonadTrans M1T where lift = M1T . lift
+
+instance Monad m => Functor (M2T m) where
+  fmap f (M2T m) = M2T $ do
+    v <- m
+    return $ f v
+instance Monad m => Applicative (M2T m) where
+  pure v = M2T $ pure v
+  (M2T m1) <*> (M2T m2) = M2T $ do
+    f <- m1
+    v <- m2
+    return (f v)
+instance Monad m => Monad (M2T m) where
+  (M2T m) >>= f = M2T $ m >>= (unwrap2 . f)
+  (M2T m1) >> (M2T m2) = M2T $ m1 >> m2
+  return v = M2T $ return v
+instance MonadTrans M2T where lift = M2T . lift
+
+instance MonadTLT m n => MonadTLT (M1T m) n where
+  liftTLT = lift . liftTLT
+instance MonadTLT m n => MonadTLT (M2T m) n where
+  liftTLT = lift . liftTLT
+
+ttest = do
+  runM1T $ inGroup "M1T tests" $ m1tests
+  runM2T $ inGroup "M2T tests" $ m2tests
+
+m1tests = M1T $ do
+  "3 is 3 as pure assertion" ~: 3 @==- 3
+  "4 is 4 as pure assertion" ~: 4 @==- 4
+
+m2tests = M2T $ do
+  "5 is 5 as pure assertion" ~: 5 @==- 5
+  "6 is 6 as pure assertion" ~: 6 @==- 6
+