diff --git a/ChangeLog.md b/ChangeLog.md
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+# Changelog for composite-xstep
+
+## (v0.1.0.0)
+
+* Initial commit - Higher kinded ReaderT transformer pattern for composite records.
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright Author name here (c) 2020
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
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+++ b/README.md
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+# composite-xstep
+
+This package provides a specific XRec pattern for [composite](https://hackage.haskell.org/package/composite) records, where the interpretation functor is isomorphic to `ReaderT r m`.
+
+For example
+
+```
+import Path
+import Composite.Record
+import Composite.TH
+
+withLensesAndProxies [d|
+  type FPath          = "path"            :-> Path Rel File
+  type FPath2         = "path2"           :-> Path Rel File
+  |]
+
+type A = '[FPath, FPath2]
+
+foo :: MonadThrow m => XStep m FilePath A
+foo =  parseRelDir
+   ::& stripProperPrefix $(mkRelFile "foo") =<< parseRelDir
+   ::& XRNil
+```
diff --git a/composite-xstep.cabal b/composite-xstep.cabal
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+++ b/composite-xstep.cabal
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+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.34.2.
+--
+-- see: https://github.com/sol/hpack
+
+name:           composite-xstep
+version:        0.1.0.0
+synopsis:       ReaderT transformer pattern for higher kinded composite data.
+description:    ReaderT transformer pattern for higher kinded composite data.
+category:       Data Structures
+author:         Daniel Firth
+maintainer:     dan.firth@homotopic.tech
+copyright:      2020 Daniel Firth
+license:        MIT
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+source-repository head
+  type: git
+  location: https://gitlab.com/homotopic-tech/composite-xstep
+
+library
+  exposed-modules:
+      Composite.XStep
+  other-modules:
+      Paths_composite_xstep
+  hs-source-dirs:
+      src
+  ghc-options: -Wall -Wcompat -Wincomplete-record-updates -Wincomplete-uni-patterns -Wredundant-constraints
+  build-depends:
+      base >=4.7 && <5
+    , composite-base
+    , vinyl
+  default-language: Haskell2010
diff --git a/src/Composite/XStep.hs b/src/Composite/XStep.hs
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--- /dev/null
+++ b/src/Composite/XStep.hs
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+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE TypeFamilies          #-}
+{-# LANGUAGE TypeOperators         #-}
+{- |
+   Module     : Composite.XStep
+   License    : MIT
+   Stability  : experimental
+
+Tuple functions for composite records, inspired by relude.
+-}
+
+module Composite.XStep (
+  RSource(runSource)
+, RSource'
+, XStep
+, XStep'
+, runSourceI
+, runXStep
+, prependXStep
+) where
+
+import Composite.Record
+import Data.Functor.Identity
+import Data.Vinyl
+import Data.Vinyl.TypeLevel
+import Data.Vinyl.XRec
+
+-- | An `RSource` is simply a `ReaderT` transformer. This is a uniquely named
+-- type as composte and vinyl aren't compatible via the `IsoHKD` interface due
+-- to the way that `(:->)` is defined.
+newtype RSource r m a = RSource { runSource :: r -> m a }
+
+-- | The special case where the environment is a `Record`.
+type RSource' r = RSource (Record r)
+
+instance Functor m => IsoHKD (RSource r m) (s :-> a) where
+  type HKD (RSource r m) (s :-> a) = r -> m a
+  unHKD f = RSource $ fmap Val . f
+  toHKD (RSource f) = fmap getVal . f
+
+-- | An `XStep` is a n `XRec` with an `RSource`. The type is eta-reduced, but in practice signatures will be written `XStep m a b` to represent a Kleisli arrow from a to m b.
+type XStep m a = XRec (RSource a m)
+
+-- | The special case where the environment is a `Record`.
+type XStep' m a = XStep m (Record a)
+
+-- | Run an `RSource` against a `Record` and pull out the underlying functor.
+runSourceI :: Functor m => RSource r m a -> r -> m (Identity a)
+runSourceI x = fmap Identity . runSource x
+
+-- | Run an `XStep` to completion.
+runXStep :: (IsoXRec (RSource a m) b, Applicative m) => XStep m a b -> a -> m (Record b)
+runXStep x y = rtraverse (`runSourceI` y) (fromXRec x)
+
+-- | The special case where the environnent is a XStep environment is `Record`, and the result should be prepended extensibly.
+prependXStep :: (IsoXRec (RSource' a m) b, Applicative m) => XStep' m a b -> Record a -> m (Record (b ++ a))
+prependXStep f x = (<+> x) <$> runXStep f x