You don't even need that, there is a much more efficient way in a language that supports let-bindings (but not letrec): let f' = func(f, g, other_args...)

You don't even need that, there is a much more efficient way in a language that supports let-bindings (but not letrec): let f' = func(f, g, other_args...) { // ... g(f, g, whatever...); // ... }; let g' = func(f, g, other_args...) { // ... f(f, g, whatever...); // ... } let f = func(other_args...) { return f'(f', g', other_args...); } let g = func(other_args...) { return g'(f', g', other_args...); } That's basically just closure conversion, only instead of doing it the compiler backend, you do it manually yourself.