diff --git a/prim.cabal b/prim.cabal
--- a/prim.cabal
+++ b/prim.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.4
 name: prim
 homepage: https://github.com/daig/prim#readme
-version: 0.1.0.1
+version: 0.1.0.2
 category: Prelude
 synopsis: An ergonomic but conservative interface to ghc-prim
 description: 
@@ -37,7 +37,7 @@
   exposed-modules: Char
                  , I64, I32, I16, I8
                  , U64, U32, U16, U8
-                 , B8, B16, B32, B64
+                 , B, B8, B16, B32, B64
                  , F64, F32
                  , ST,ST.IO, ST.IO.STM
                  , Ref
diff --git a/src/B.hs b/src/B.hs
new file mode 100644
--- /dev/null
+++ b/src/B.hs
@@ -0,0 +1,5 @@
+module B (B, module B) where
+
+fromI64 :: I64 -> B
+fromI64 = andI# 1#
+
diff --git a/src/I16.hs b/src/I16.hs
--- a/src/I16.hs
+++ b/src/I16.hs
@@ -1,1 +1,18 @@
-module I16 (I16) where
+module I16 (I16, module I16) where
+
+fromI64 :: I64 -> I16
+fromI64 = narrow16Int#
+
+add, sub, mul, quot, rem :: I16 -> I16 -> I16
+add y x = narrow16Int# (x +# y)
+sub y x = narrow16Int# (x -# y)
+mul y x = narrow16Int# (x *# y)
+quot y x = narrow16Int# (quotInt# x y)
+rem y x = narrow16Int# (remInt# x y)
+
+quotRem :: I16 -> I16 -> (# I16, I16 #)
+quotRem y x = case quotRemInt# x y of
+  (# q, r #) -> (# narrow16Int# q, narrow16Int# r #)
+
+shiftL# :: I64 -> I16 -> I16
+shiftL# i x = narrow16Int# (uncheckedIShiftL# x i)
diff --git a/src/I32.hs b/src/I32.hs
--- a/src/I32.hs
+++ b/src/I32.hs
@@ -1,1 +1,18 @@
-module I32 (I32) where
+module I32 (I32, module I32) where
+
+fromI64 :: I64 -> I32
+fromI64 = narrow32Int#
+
+add, sub, mul, quot, rem :: I32 -> I32 -> I32
+add y x = narrow32Int# (x +# y)
+sub y x = narrow32Int# (x -# y)
+mul y x = narrow32Int# (x *# y)
+quot y x = narrow32Int# (quotInt# x y)
+rem y x = narrow32Int# (remInt# x y)
+
+quotRem :: I32 -> I32 -> (# I32, I32 #)
+quotRem y x = case quotRemInt# x y of
+  (# q, r #) -> (# narrow32Int# q, narrow32Int# r #)
+
+shiftL# :: I64 -> I32 -> I32
+shiftL# i x = narrow32Int# (uncheckedIShiftL# x i)
diff --git a/src/I64.hs b/src/I64.hs
--- a/src/I64.hs
+++ b/src/I64.hs
@@ -93,13 +93,13 @@
 -- | Shift left.  Result undefined if shift amount is not
 --           in the range 0 to word size - 1 inclusive.
 shiftL# :: I64 -> I64 -> I64
-shiftL# = uncheckedIShiftL# 
+shiftL# i x = uncheckedIShiftL# x i
 
 -- |Shift right logical.  Result undefined if shift amount is not
 --           in the range 0 to word size - 1 inclusive.
 
 shiftRL# :: I64 -> I64 -> I64
-shiftRL# = uncheckedIShiftRL#
+shiftRL# i x = uncheckedIShiftRL# x i
 and, or, xor :: I64 -> I64 -> I64
 and = andI#
 or = orI#
diff --git a/src/I8.hs b/src/I8.hs
--- a/src/I8.hs
+++ b/src/I8.hs
@@ -1,1 +1,18 @@
-module I8 (I8) where
+module I8 (I8, module I8) where
+
+fromI64 :: I64 -> I8
+fromI64 = narrow8Int#
+
+add, sub, mul, quot, rem :: I8 -> I8 -> I8
+add y x = narrow8Int# (x +# y)
+sub y x = narrow8Int# (x -# y)
+mul y x = narrow8Int# (x *# y)
+quot y x = narrow8Int# (quotInt# x y)
+rem y x = narrow8Int# (remInt# x y)
+
+quotRem :: I8 -> I8 -> (# I8, I8 #)
+quotRem y x = case quotRemInt# x y of
+  (# q, r #) -> (# narrow8Int# q, narrow8Int# r #)
+
+shiftL# :: I64 -> I8 -> I8
+shiftL# i x = narrow8Int# (uncheckedIShiftL# x i)
diff --git a/src/U16.hs b/src/U16.hs
--- a/src/U16.hs
+++ b/src/U16.hs
@@ -1,1 +1,9 @@
-module U16 (U16) where
+module U16 (U16, module U16) where
+
+fromU64 :: U64 -> U16
+fromU64 = narrow16Word#
+
+add, sub, mul :: U16 -> U16 -> U16
+add y x = narrow16Word# (plusWord# x y)
+sub y x = narrow16Word# (minusWord# x y)
+mul y x = narrow16Word# (timesWord# x y)
diff --git a/src/U32.hs b/src/U32.hs
--- a/src/U32.hs
+++ b/src/U32.hs
@@ -1,2 +1,9 @@
-module U32 (U32) where
+module U32 (U32, module U32) where
 
+fromU64 :: U64 -> U32
+fromU64 = narrow32Word#
+
+add, sub, mul :: U32 -> U32 -> U32
+add y x = narrow32Word# (plusWord# x y)
+sub y x = narrow32Word# (minusWord# x y)
+mul y x = narrow32Word# (timesWord# x y)
diff --git a/src/U8.hs b/src/U8.hs
--- a/src/U8.hs
+++ b/src/U8.hs
@@ -1,1 +1,9 @@
-module U8 (U8) where
+module U8 (U8, module U8) where
+
+fromU64 :: U64 -> U8
+fromU64 = narrow8Word#
+
+add, sub, mul :: U8 -> U8 -> U8
+add y x = narrow8Word# (plusWord# x y)
+sub y x = narrow8Word# (minusWord# x y)
+mul y x = narrow8Word# (timesWord# x y)