| 116 | === Fourth report === |

| 117 | |

| 118 | Ron de Bruijn ([email protected]) reported: |

| 119 | {{{ |

| 120 | [set_left_child_leaf, set_right_child_leaf] = map set_gen_child_leaf [l, r] |

| 121 | }}} |

| 122 | Here "l" and "r" are functions that get the left and right child of a tree and |

| 123 | set_gen_child is a function generalized over the type of child being |

| 124 | selected. |

| 125 | |

| 126 | The above doesn't work on GHC 6.6.1. I get |

| 127 | {{{ |

| 128 | Cannot match a monotype with `forall s |

| 129 | a |

| 130 | (chain :: * -> * -> *) |

| 131 | (m :: * -> *). |

| 132 | STRef s (Node s a chain) -> m ()' |

| 133 | }}} |

| 134 | The only other sane way to get this working is to unroll the map by hand. |

| 135 | |

| 136 | |