diff --git a/runtime/sam/expr/function/cast.go b/runtime/sam/expr/function/cast.go
index 18158b652..996e25e75 100644
--- a/runtime/sam/expr/function/cast.go
+++ b/runtime/sam/expr/function/cast.go
@@ -24,6 +24,7 @@ func NewCaster(sctx *super.Context) Caster {
 
 func (c *cast) Call(args []super.Value) super.Value {
 	from, to := args[0], args[1]
+	from = from.SuperDeunion()
 	if from.IsError() {
 		return from
 	}
diff --git a/runtime/vam/expr/cast.go b/runtime/vam/expr/cast.go
index 4ffaf158c..408d29939 100644
--- a/runtime/vam/expr/cast.go
+++ b/runtime/vam/expr/cast.go
@@ -39,7 +39,7 @@ type casterPrimitive struct {
 }
 
 func (c *casterPrimitive) Eval(this vector.Any) vector.Any {
-	return vector.Apply(vector.ApplyRipUnions, func(vecs ...vector.Any) vector.Any {
+	return vector.Apply(vector.ApplyRipFusions|vector.ApplyRipUnions, func(vecs ...vector.Any) vector.Any {
 		return cast.To(c.sctx, vecs[0], c.typ)
 	}, c.expr.Eval(this))
 }
@@ -51,7 +51,7 @@ type casterNamedType struct {
 }
 
 func (c *casterNamedType) Eval(this vector.Any) vector.Any {
-	return vector.Apply(vector.ApplyNone, c.eval, c.expr.Eval(this))
+	return vector.Apply(vector.ApplyRipFusions|vector.ApplyRipUnions, c.eval, c.expr.Eval(this))
 }
 
 func (c *casterNamedType) eval(vecs ...vector.Any) vector.Any {
diff --git a/runtime/ztests/expr/cast/bool.yaml b/runtime/ztests/expr/cast/bool.yaml
index 98386fecd..5af096966 100644
--- a/runtime/ztests/expr/cast/bool.yaml
+++ b/runtime/ztests/expr/cast/bool.yaml
@@ -14,6 +14,7 @@ input: |
   "true"
   "F"
   "false"
+  fusion("false"::(string|null),<string>)
   "blah"
   null
   null::({}|null)
@@ -38,6 +39,7 @@ output: |
   true
   false
   false
+  false
   error({message:"cannot cast to bool",on:"blah"})
   null::(bool|null)
   null::(bool|null)
diff --git a/runtime/ztests/expr/cast/bytes.yaml b/runtime/ztests/expr/cast/bytes.yaml
index 8178f385a..7d6c6992f 100644
--- a/runtime/ztests/expr/cast/bytes.yaml
+++ b/runtime/ztests/expr/cast/bytes.yaml
@@ -6,6 +6,7 @@ input: |
   type named=string
   "bar"::named
   ""
+  fusion("a"::(string|null),<string>)
   null
   null::({}|null)
   {x:"foo"}
@@ -17,6 +18,7 @@ output: |
   0x666f6f
   0x626172
   0x
+  0x61
   null::(bytes|null)
   null::(bytes|null)
   error({message:"cannot cast to bytes",on:{x:"foo"}})
diff --git a/runtime/ztests/expr/cast/duration.yaml b/runtime/ztests/expr/cast/duration.yaml
index 69bf23713..3e5a28968 100644
--- a/runtime/ztests/expr/cast/duration.yaml
+++ b/runtime/ztests/expr/cast/duration.yaml
@@ -8,6 +8,7 @@ input: |
   -1.5e12
   type named=int64
   1::named
+  fusion(2::named::(named|null),<named>)
   1e+19
   null
   null::({}|null)
@@ -25,6 +26,7 @@ output: |
   error({message:"cannot cast to duration",on:""})
   -25m
   1ns
+  2ns
   error({message:"cannot cast to duration",on:1e+19})
   null::(duration|null)
   null::(duration|null)
diff --git a/runtime/ztests/expr/cast/enum.yaml b/runtime/ztests/expr/cast/enum.yaml
index cc0ea77cb..8fd222a8d 100644
--- a/runtime/ztests/expr/cast/enum.yaml
+++ b/runtime/ztests/expr/cast/enum.yaml
@@ -1,7 +1,8 @@
 spq: this::enum(e1,e2)
 
 input: |
-  "e2"
+  "e1"
+  fusion("e2"::(string|null),<string>)
   "e3"
   0
   null
@@ -9,6 +10,7 @@ input: |
   error("bad")
 
 output: |
+  "e1"::enum(e1,e2)
   "e2"::enum(e1,e2)
   error({message:"no such symbol in enum(e1,e2)",on:"e3"})
   error({message:"cannot cast to enum",on:0})
diff --git a/runtime/ztests/expr/cast/float.yaml b/runtime/ztests/expr/cast/float.yaml
index a754b032e..bbfe4d918 100644
--- a/runtime/ztests/expr/cast/float.yaml
+++ b/runtime/ztests/expr/cast/float.yaml
@@ -10,6 +10,7 @@ input: |
   2::named
   false
   true
+  fusion("2"::(string|null),<string>)
   null
   null::({}|null)
 
@@ -38,6 +39,9 @@ output: |
   1.::float16
   1.::float32
   1.
+  2.::float16
+  2.::float32
+  2.
   null::(float16|null)
   null::(float32|null)
   null::(float64|null)
diff --git a/runtime/ztests/expr/cast/int.yaml b/runtime/ztests/expr/cast/int.yaml
index 80d8b8eb3..0a436921c 100644
--- a/runtime/ztests/expr/cast/int.yaml
+++ b/runtime/ztests/expr/cast/int.yaml
@@ -12,6 +12,7 @@ input: |
   1e8
   false
   true
+  fusion("2"::(string|null),<string>)
   null
   null::({}|null)
 
@@ -52,6 +53,10 @@ output: |
   1::int16
   1::int32
   1
+  2::int8
+  2::int16
+  2::int32
+  2
   null::(int8|null)
   null::(int16|null)
   null::(int32|null)
diff --git a/runtime/ztests/expr/cast/ip.yaml b/runtime/ztests/expr/cast/ip.yaml
index a7eb86c4b..e51fe452f 100644
--- a/runtime/ztests/expr/cast/ip.yaml
+++ b/runtime/ztests/expr/cast/ip.yaml
@@ -4,6 +4,7 @@ input: |
   "foo"
   "127.0.0.1"
   "2001:0000:130F:0000:0000:09C0:876A:130B"
+  fusion("3000::"::(string|null),<string>)
   null
   null::({}|null)
   1.1.1.1
@@ -18,6 +19,7 @@ output: |
   error({message:"cannot cast to ip",on:"foo"})
   127.0.0.1
   2001:0:130f::9c0:876a:130b
+  3000::
   null::(ip|null)
   null::(ip|null)
   1.1.1.1
diff --git a/runtime/ztests/expr/cast/map.yaml b/runtime/ztests/expr/cast/map.yaml
index ae7fc1cb3..6e1e284f7 100644
--- a/runtime/ztests/expr/cast/map.yaml
+++ b/runtime/ztests/expr/cast/map.yaml
@@ -3,6 +3,7 @@ spq: |
 
 input: |
   map{}
+  fusion(map{1:map{2:3}}::(null|map{int64:map{int64:int64}}),<map{int64:map{int64:int64}}>)
   map{1:map{"2":3,4:"5"},"7":8,"9":map{10:[],[]:11,null:null}}
   null
   null::({}|null)
@@ -12,6 +13,7 @@ input: |
 
 output: |
   map{}
+  map{1:map{"2":3}}
   map{1:map{"2":3,"4":5},7:error({message:"cannot cast to map{string:int64}",on:8}),9:map{null:null,"10":error({message:"cannot cast to int64",on:[]}),"[]":11}}
   null::(null|map{int64:map{string:int64}})
   null::(null|map{int64:map{string:int64}})
diff --git a/runtime/ztests/expr/cast/named.yaml b/runtime/ztests/expr/cast/named.yaml
index 6b5ead2f3..752647908 100644
--- a/runtime/ztests/expr/cast/named.yaml
+++ b/runtime/ztests/expr/cast/named.yaml
@@ -5,6 +5,7 @@ spq: |
 input: |
   {x:1}
   {x:2}
+  fusion({x:3}::(null|{x:int64}),<{x:int64}>)
   "foo"
   "bar"
   type a=string
@@ -18,6 +19,7 @@ output: |
   type named={x:int64}
   {x:1}::named
   {x:2}::named
+  {x:3}::named
   error("type \"named\" redefined")
   error("type \"named\" redefined")
   error("type \"named\" redefined")
@@ -41,3 +43,4 @@ output: |
   type foo=int64
   {str:1::foo,named:1::foo}
   {str:2::foo,named:2::foo}
+
diff --git a/runtime/ztests/expr/cast/net.yaml b/runtime/ztests/expr/cast/net.yaml
index d4d1d09e7..0891fb408 100644
--- a/runtime/ztests/expr/cast/net.yaml
+++ b/runtime/ztests/expr/cast/net.yaml
@@ -3,6 +3,7 @@ spq: this::net
 input: |
   "192.168.1.0/24"
   "2001:db8::/32"
+  fusion("2001:db8::/33"::(string|null),<string>)
   null
   null::({}|null)
   10.0.0.0/8
@@ -16,6 +17,7 @@ input: |
 output: |
   192.168.1.0/24
   2001:db8::/32
+  2001:db8::/33
   null::(net|null)
   null::(net|null)
   10.0.0.0/8
diff --git a/runtime/ztests/expr/cast/record.yaml b/runtime/ztests/expr/cast/record.yaml
index 01c2f2939..3b3e98643 100644
--- a/runtime/ztests/expr/cast/record.yaml
+++ b/runtime/ztests/expr/cast/record.yaml
@@ -7,6 +7,7 @@ input: |
   {b:1,c:2}
   {a:"1",b:2,c:{cc:3},d:[{e:4,f:"5"},{f:6,e:"7"},8]}
   {d:[{e:1,f:"2"},{f:3,e:"4"},5],c:null,b:6,a:"7"}
+  fusion({a:1,b:2,c:{},d:[]}::(null|{a:int64,b:int64,c:{},d:[none]}),<{a:int64,b:int64,c:{},d:[none]}>)
   null
   null::({}|null)
   1
@@ -19,6 +20,7 @@ output: |
   {a:error("missing"),b:"1",c:error({message:"cannot cast to {}",on:2}),d:error("missing")}
   {a:1,b:"2",c:{},d:[{e:"4",f:5},{e:"7",f:6},error({message:"cannot cast to {e:string,f:int64}",on:8})]}
   {a:7,b:"6",c:null::(null|{}),d:[{e:"1",f:2},{e:"4",f:3},error({message:"cannot cast to {e:string,f:int64}",on:5})]}
+  {a:1,b:"2",c:{},d:[]::[{e:string,f:int64}]}
   null::(null|{a:int64,b:string,c:{},d:[{e:string,f:int64}]})
   null::(null|{a:int64,b:string,c:{},d:[{e:string,f:int64}]})
   error({message:"cannot cast to {a:int64,b:string,c:{},d:[{e:string,f:int64}]}",on:1})
diff --git a/runtime/ztests/expr/cast/string.yaml b/runtime/ztests/expr/cast/string.yaml
index d15bfc460..68267d989 100644
--- a/runtime/ztests/expr/cast/string.yaml
+++ b/runtime/ztests/expr/cast/string.yaml
@@ -30,6 +30,7 @@ input: |
   {foo:"bar"}
   [1,2,3]
   "e2"::enum(e1,e2)
+  fusion(1::(int64|null),<int64>)
   error("bad")
 
 output: |
@@ -61,4 +62,5 @@ output: |
   "{foo:\"bar\"}"
   "[1,2,3]"
   "e2"
+  "1"
   error("bad")
diff --git a/runtime/ztests/expr/cast/time.yaml b/runtime/ztests/expr/cast/time.yaml
index e3f6086d8..7865d6c6b 100644
--- a/runtime/ztests/expr/cast/time.yaml
+++ b/runtime/ztests/expr/cast/time.yaml
@@ -11,6 +11,7 @@ input: |
   "foo"
   -1e9
   1
+  fusion(1::(int64|null),<int64>)
   null
   null::({}|null)
   1e200
@@ -31,6 +32,7 @@ output: |
   error({message:"cannot cast to time",on:"foo"})
   1969-12-31T23:59:59Z
   1970-01-01T00:00:00.000000001Z
+  1970-01-01T00:00:00.000000001Z
   null::(time|null)
   null::(time|null)
   error({message:"cannot cast to time",on:1e+200})
diff --git a/runtime/ztests/expr/cast/type.yaml b/runtime/ztests/expr/cast/type.yaml
index 463e88bdd..86508c539 100644
--- a/runtime/ztests/expr/cast/type.yaml
+++ b/runtime/ztests/expr/cast/type.yaml
@@ -4,6 +4,7 @@ input: |
   "<int64>"
   <ip>
   "<{x:string}>"
+  fusion("<{x:string}>"::(string|null),<string>)
   "{x:\"foo\"}"
   "<int>"
   1
@@ -11,11 +12,13 @@ input: |
   null
   null::({}|null)
   error("bad")
+  fusion(error(1)::(error(int64)|int64),<error(int64)>)
 
 output: |
   <int64>
   <ip>
   <{x:string}>
+  <{x:string}>
   error({message:"cannot cast to type",on:"{x:\"foo\"}"})
   error({message:"cannot cast to type",on:"<int>"})
   error({message:"cannot cast to type",on:1})
@@ -23,3 +26,4 @@ output: |
   null::(type|null)
   null::(type|null)
   error("bad")
+  error(1)
diff --git a/runtime/ztests/expr/cast/uint.yaml b/runtime/ztests/expr/cast/uint.yaml
index 99d174593..0544c46f2 100644
--- a/runtime/ztests/expr/cast/uint.yaml
+++ b/runtime/ztests/expr/cast/uint.yaml
@@ -4,6 +4,7 @@ spq: |
 input: |
   false
   true
+  fusion(true::(bool|null),<bool>)
   -1
   null
   null::({}|null)
@@ -18,6 +19,10 @@ output: |
   1::uint16
   1::uint32
   1::uint64
+  1::uint8
+  1::uint16
+  1::uint32
+  1::uint64
   error({message:"cannot cast to uint8",on:-1})
   error({message:"cannot cast to uint16",on:-1})
   error({message:"cannot cast to uint32",on:-1})