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### view tests/functor.lac @ 46:44a1bc863f0f

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Corifying functors

author | Adam Chlipala <adamc@hcoop.net> |
---|---|

date | Thu, 19 Jun 2008 17:55:36 -0400 |

parents | a9f3ce2d1b9b |

children | ac4c0b4111ba |

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signature S = sig type t val z : t val s : t -> t end signature T = sig type t val three : t end functor F (M : S) : T where type t = M.t = struct type t = M.t val three = M.s (M.s (M.s M.z)) end structure O = F (struct type t = int val z = 0 val s = fn x : t => x end) val three : int = O.three structure S = struct type t = int val z = 0 val s = fn x : t => x end structure SO = F (S) val three : int = SO.three structure SS : S = S structure SSO = F (SS) val three : SS.t = SSO.three