diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # j
 
+## 0.2.2.0
+
+  * Add `tryIntVect` and `copyIntVect`
+
 ## 0.2.1.1
 
   * Test suite works with J 9.02
diff --git a/j.cabal b/j.cabal
--- a/j.cabal
+++ b/j.cabal
@@ -1,6 +1,6 @@
 cabal-version:   1.18
 name:            j
-version:         0.2.1.1
+version:         0.2.2.0
 license:         BSD3
 license-file:    LICENSE
 copyright:       Copyright: (c) 2020 Vanessa McHale
@@ -27,7 +27,8 @@
     build-depends:
         base >=4.8 && <5,
         bytestring >=0.10,
-        repa >=3.2.5.0
+        repa >=3.2.5.0,
+        vector >=0.5
 
     if !os(windows)
         build-depends: unix >=2.7.0.0
diff --git a/src/Language/J.hs b/src/Language/J.hs
--- a/src/Language/J.hs
+++ b/src/Language/J.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP               #-}
+{-# LANGUAGE DeriveAnyClass    #-}
 {-# LANGUAGE FlexibleContexts  #-}
 {-# LANGUAGE OverloadedStrings #-}
 
@@ -91,6 +92,11 @@
                   , JData (..)
                   , getJData
                   , setJData
+                  -- * Exceptions
+                  , JErr (..)
+                  -- * Vector helpers
+                  , tryIntVect
+                  , copyIntVect
                   -- * FFI
                   , J
                   , JDoType
@@ -100,6 +106,7 @@
                   ) where
 
 import           Control.Applicative             (pure, (<$>), (<*>))
+import           Control.Exception               (Exception, throw)
 import qualified Data.Array.Repa                 as R
 import qualified Data.Array.Repa.Repr.ForeignPtr as RF
 import qualified Data.ByteString                 as BS
@@ -108,6 +115,7 @@
 import           Data.Complex                    (Complex (..))
 import           Data.Functor                    (void)
 import           Data.Semigroup                  ((<>))
+import qualified Data.Vector.Unboxed             as V
 import           Foreign.C.String                (CString)
 import           Foreign.C.Types                 (CChar, CDouble, CInt (..), CLLong (..))
 import           Foreign.ForeignPtr              (ForeignPtr, castForeignPtr, mallocForeignPtrBytes, withForeignPtr)
@@ -237,7 +245,6 @@
     JEnv jt <$> jeval <*> jread <*> jOut <*> jSet
 #endif
 
-
 -- | Send some J code to the environment.
 bsDispatch :: JEnv -> BS.ByteString -> IO ()
 bsDispatch (JEnv ctx jdo _ _ _) bs =
@@ -250,6 +257,8 @@
 bsOut (JEnv ctx _ _ jout _) = BS.packCString =<< jout ctx
 
 -- | \( O(n) \) in the array size
+--
+-- Throws 'JErr' for unspported conversion types.
 getJData :: R.Shape sh
          => JEnv -> BS.ByteString -- ^ Name of the value in question
          -> IO (JData sh)
@@ -286,6 +295,23 @@
               | JBoolArr !(R.Array RF.F sh CChar)
               | JString !BS.ByteString
 
+data JErr = TypeError
+          | UnsupportedType
+          deriving (Show, Exception)
+
+-- | Copy into a 'V.Vector' 'Int', if possible.
+--
+-- Throws a 'JErr' on type error.
+--
+-- \( O(n) \)
+tryIntVect :: JData R.DIM1 -> V.Vector Int
+tryIntVect (JIntArr arr) = R.toUnboxed (R.copyS $ R.map fromIntegral arr)
+tryIntVect _             = throw TypeError
+
+-- | \( O(n) \)
+copyIntVect :: V.Vector Int -> JData R.DIM1
+copyIntVect = JIntArr . R.copyS . R.map fromIntegral . (\v -> R.fromUnboxed (R.ix1 $ V.length v) v)
+
 -- | \( O(n) \) in the array size
 setJData :: (R.Shape sh) => JEnv -> BS.ByteString -- ^ Name
                          -> JData sh -> IO CInt
@@ -312,7 +338,7 @@
 repaArr jty arr = do
     let (rank', sh) = repaSize arr
         sz = product sh
-    let wid = 32 + (fromIntegral $ jTypeWidth jty) * (rank' + sz)
+    let wid = 32 + fromIntegral (jTypeWidth jty) * (rank' + sz)
     ptr <- mallocBytes (fromIntegral wid)
     pokeByteOff ptr 0 (227 :: CLLong) -- I think this is because it's non-boxed
     pokeByteOff ptr (sizeOf (undefined :: CLLong)) (jTypeToInt jty)
@@ -357,7 +383,7 @@
 intToJType 4  = JInteger
 intToJType 8  = JDouble
 intToJType 16 = JComplex
-intToJType _  = error "Unsupported type!"
+intToJType _  = throw UnsupportedType
 
 jTypeToInt :: JType -> CLLong
 jTypeToInt JBool    = 1