diff --git a/examples/README.jl b/examples/README.jl
index 48273fc..b619abf 100644
--- a/examples/README.jl
+++ b/examples/README.jl
@@ -28,16 +28,16 @@ using SparseArraysBaseNext: SparseArrayInterface
 
 ## @derive SparseArrayInterface (T=SparseArrayDOK) Base.getindex(::T, ::Int...)
 
-@derive SparseArrayInterface begin
-  Base.getindex(::SparseArrayDOK, ::Int...)
-  Base.setindex!(::SparseArrayDOK, ::Any, ::Int...)
-end
-
-## @derive (T=SparseArrayDOK,) begin
-##   Base.getindex(::T, ::Int...)
-##   Base.setindex!(::T, ::Any, ::Int...)
+## @derive SparseArrayInterface begin
+##   Base.getindex(::SparseArrayDOK, ::Int...)
+##   Base.setindex!(::SparseArrayDOK, ::Any, ::Int...)
 ## end
 
+@derive (T=SparseArrayDOK,) begin
+  Base.getindex(::T, ::Int...)
+  Base.setindex!(::T, ::Any, ::Int...)
+end
+
 ## @derive SparseArrayInterface (T=SparseArrayDOK) begin
 ##   Base.getindex(::T, ::Int...)
 ##   Base.setindex!(::T, ::Any, ::Int...)
diff --git a/src/lib/Derive/derive_macro.jl b/src/lib/Derive/derive_macro.jl
index 781a8b4..e303041 100644
--- a/src/lib/Derive/derive_macro.jl
+++ b/src/lib/Derive/derive_macro.jl
@@ -15,7 +15,7 @@ end
 
 function globalref_derive(expr)
   return @match expr begin
-    :(Derive.$f($(x...))) => :($(GlobalRef(Derive, :($f)))($(x...)))
+    :(Derive.$f) => :($(GlobalRef(Derive, :($f))))
     e::Expr => Expr(e.head, map(globalref_derive, e.args)...)
     a => a
   end
@@ -93,7 +93,7 @@ end
 
 argname(i::Int) = Symbol(:arg, i)
 
-function derive_interface_func(interface::Expr, func::Expr)
+function derive_interface_func(interface::Union{Symbol,Expr}, func::Expr)
   name, args, kwargs, whereparams, rettype = split_function_head(func)
   argnames = map(argname, 1:length(args))
   named_args = map(1:length(args)) do i
@@ -122,29 +122,31 @@ function derive_interface_func(interface::Expr, func::Expr)
   jlfn = JLFunction(; name, args=named_args, kwargs, whereparams, rettype, body)
   # Use `globalref_derive` to not require having `Derive` in the
   # namespace when `@derive` is called.
-  return @show globalref_derive(codegen_ast(jlfn))
+  return globalref_derive(codegen_ast(jlfn))
 end
 
 function derive_func(types::Expr, func::Expr)
   Meta.isexpr(types, :tuple) && all(arg -> Meta.isexpr(arg, :(=)), types.args) ||
     error("Wrong types format.")
   name, args, kwargs, whereparams, rettype = split_function_head(func)
-
-  @show types
-  @show func
-  @show args
-
-  args = map
-  for type in types.args
-    @show type
-    @show type.args[1]
-    @show type.args[2]
-
-    args = Expr
+  new_args = args
+  for type_expr in types.args
+    typevar, type = @match type_expr begin
+      :($x = $y) => (x, y)
+    end
+    new_args = map(args) do arg
+      return @match arg begin
+        :(::$T) => T == typevar ? :(::$type) : :(::$T)
+        :(::$T...) => T == typevar ? :(::$type...) : :(::$T...)
+      end
+    end
   end
-
-  error()
-  return derive_func(interface, func)
+  active_argnames = map(argname, findall(args .≠ new_args))
+  interface = globalref_derive(:(Derive.AbstractInterface(Derive.AbstractInterface.(($(active_argnames...),))...)))
+  _, func, _ = split_function(
+    codegen_ast(JLFunction(; name, args=new_args, kwargs, whereparams, rettype))
+  )
+  return derive_interface_func(interface, func)
 end
 
 function derive(::Val{:AbstractArrayOps})