| 19 | |

| 20 | If we encounter an instance declaration for `C tau` during conversion, there are two alternatives: we have a conversion for `C` or not: |

| 21 | * if we do not have a conversion, we generate an instance (and hence dfun) for `C tau^`, where `tau^` is the closure converted `tau`; |

| 22 | * if we have a conversion, we generate an instance for `C_CC tau^`. |

| 23 | In any case, we add a field `is_CC :: Just Instance` to `InstEnv.Instance` that contains the additionally generated instance. And in both cases, we should be able to derive the required code for the dfun from the definition of `C tau`. |

| 24 | |

| 25 | === Type terms === |

| 26 | |

| 27 | We determine the converted type `t^` of `t` as follows: |

| 28 | {{{ |

| 29 | T^ = T_CC , if available |

| 30 | T , otherwise |

| 31 | a^ = a |

| 32 | (t1 t2)^ = t1^ t2^ |

| 33 | (t1 -> t2)^ = Clo t1 t2 |

| 34 | (forall a.t)^ = forall a.t^ |

| 35 | (C t1 => t2)^ = C_CC t1^ => t2^ , if available |

| 36 | C t1^ => t2^ , otherwise |

| 37 | }}} |

| 38 | |

| 39 | === Value bindings === |

| 40 | |

| 41 | When converting a toplevel binding for `f :: t`, we generate `f_CC :: t^`. The alternatives `GlobalId` and `LocalId` of `Var.Var` get a new field `idCC :: Maybe Id` and the `Id` for `f` contains `Just f_CC` in that field. |