diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # Changelog
 
+Version 0.1.2.0
+---------------
+
+*October 4, 2019*
+
+<https://github.com/mstksg/backprop/releases/tag/v0.1.2.0>
+
+*   Add `expandFin` and `unexpandFin`, meant to make conversion between
+    `Pointed` and `Finite` more streamlined.
+
 Version 0.1.1.1
 ---------------
 
diff --git a/bins.cabal b/bins.cabal
--- a/bins.cabal
+++ b/bins.cabal
@@ -1,11 +1,13 @@
--- This file has been generated from package.yaml by hpack version 0.28.2.
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.31.2.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: d3a0afd067f13ba2e886ad66828fdb40215329e79a93de097003e945e182473d
+-- hash: 2d39bb70debd2683b6b3f7d4d013a5358e519b6b21cf2eb6af0a98fb6292d10e
 
 name:           bins
-version:        0.1.1.1
+version:        0.1.2.0
 synopsis:       Aggregate continuous values into discrete bins
 description:    Please see the README on GitHub at <https://github.com/mstksg/bins#readme>
 category:       Math
@@ -16,11 +18,11 @@
 copyright:      (c) Justin Le 2018
 license:        BSD3
 license-file:   LICENSE
+tested-with:    GHC >= 8.2
 build-type:     Simple
-cabal-version:  >= 1.10
 extra-source-files:
-    CHANGELOG.md
     README.md
+    CHANGELOG.md
 
 source-repository head
   type: git
diff --git a/src/Data/Bin.hs b/src/Data/Bin.hs
--- a/src/Data/Bin.hs
+++ b/src/Data/Bin.hs
@@ -47,7 +47,7 @@
   -- ** Showing bins
   , displayBin, displayBinDouble
   -- *** In-depth inspection
-  , Pointed(..), pointed, pElem, binIx, fromIx
+  , Pointed(..), pointed, pElem, binIx, fromIx, expandFin, unexpandFin
   -- * Untyped
   , SomeBin(..), sameBinSpec
   -- * Handy use patterns
@@ -238,7 +238,7 @@
     :: KnownNat n
     => Bin s n
     -> Finite (1 + n + 1)
-binFinExt = pointed minBound (weaken . shift) maxBound . binIx
+binFinExt = expandFin . binIx
 
 -- | Like 'binFin', but squishes or compresses "below minimum" to "above
 -- maximum" bins into the 'Finite', counting them in the same bin as the
@@ -444,6 +444,25 @@
 -- as well.
 fromFin :: Finite n -> Bin s n
 fromFin = fromIx . PElem
+
+-- | "Expand" a 'Pointed' containing a 'Finite' to a wider-ranged 'Finite'.
+-- Used for 'binFinExt'
+--
+-- @since 0.1.2.0
+expandFin :: KnownNat n => Pointed (Finite n) -> Finite (1 + n + 1)
+expandFin = pointed minBound (weaken . shift) maxBound
+
+-- | The inverse of 'expandFin': "re-pack" a 'Finite' back into
+-- a 'Pointed' containing a narrower-ranged 'Finite'.
+--
+-- @since 0.1.2.0
+unexpandFin :: KnownNat n => Finite (1 + n + 1) -> Pointed (Finite n)
+unexpandFin x = case unshift x of
+  Nothing -> Bot
+  Just y  -> case strengthen y of
+    Nothing -> Top
+    Just z  -> PElem z
+
 
 -- | A @'SomeBin' a n@ is @'Bin' s n@, except with the 'BinSpec' s hidden.
 -- It's useful for returning out of 'withBinner'.