message: encode variance in F
diff: @@ -9,7 +9,7 @@ export type UF_ = typeof UF_
  export interface F__<E, A> {
  URI: UF__
  - E: E
  + E: () => E
  A: A
  }
  @@ -19,9 +19,9 @@ export type UF__ = typeof UF__
  export interface F___<R, E, A> {
  URI: UF___
  - E: E
  + R: (_: R) => void
  + E: () => E
  A: A
  - R: R
  }
  export const UF___ = "F___"
  @@ -30,10 +30,10 @@ export type UF___ = typeof UF___
  export interface F____<S, R, E, A> {
  URI: UF____
  - E: E
  - A: A
  - R: R
  S: S
  + R: (_: R) => void
  + E: () => E
  + A: A
  }
  export const UF____ = "F____"
  