simple derive utility macro

src/Flux.jl

@@ -1,6 +1,6 @@
 module Flux
 
-using Lazy, Flow
+using MacroTools, Lazy, Flow
 
 # Zero Flux Given
 

src/rt/diff.jl

@@ -22,3 +22,12 @@ function ∇graph(v::IVertex, ∇, out = d())
   end
   return out
 end
+
+macro derive(ex)
+  v = vertex(Flow.Do())
+  for (k, x) in ∇graph(il(graphm(resolve_calls(ex))), @flow(∇))
+    k = Symbol("∇", k)
+    thread!(v, @v(Flow.Assign(k)(x)))
+  end
+  Expr(:quote, @> v cse syntax prettify)
+end