Proxy package:pipes

A Proxy is a monad transformer that receives and sends information on both an upstream and downstream interface. The type variables signify:
  • a' and a - The upstream interface, where (a')s go out and (a)s come in
  • b' and b - The downstream interface, where (b)s go out and (b')s come in
  • m - The base monad
  • r - The return value