created function merge macro

src/ForceImport.jl

@@ -4,7 +4,7 @@ module ForceImport
 #   This file is part of ForceImport.jl. It is licensed under the MIT license
 #   Copyright (C) 2018 Michael Reed
 
-export @force
+export @force, @merge
 
 """
 
@@ -42,6 +42,32 @@ macro port(use)
     return Expr(:block,out...)
 end
 
+"""
+
+        @merge fun(x) = x
+
+Automatically imports `fun` from its module if necessary for function definition.
+"""
+macro merge(expr)
+    if !( (expr.head == :function) | ( (expr.head == :(=)) &&
+            (typeof(expr.args[1]) == Expr) && (expr.args[1].head == :call) ) )
+        throw(error("ForceImport: $expr is not a function definition"))
+    end
+    fun = expr.args[1].args[1]
+    return Expr(:quote,quote
+        for name in names(current_module())
+            try
+                eval(ForceImport.imp($(string(fun)),name))
+            end
+        end
+        eval($(Expr(:quote,expr)))
+    end)
+end
+
+function imp(fun::String,name::Symbol)
+    :(Symbol($fun) ∈ names($name) && (import $name.$(Symbol(fun))))
+end
+
 __init__() = nothing
 
 end # module