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annotate tests/type_class.ur @ 675:43430b7190f4

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Type class inclusions
author Adam Chlipala <adamc@hcoop.net>
date Thu, 26 Mar 2009 15:13:36 -0400
parents fab5998b840e
children 81573f62d6c3
rev   line source
adamc@674 1 datatype pair a b = Pair of a * b
adamc@211 2
adamc@674 3 structure M : sig
adamc@674 4 class default
adamc@674 5 val get : t ::: Type -> default t -> t
adamc@211 6
adamc@674 7 val string_default : default string
adamc@674 8 val int_default : default int
adamc@212 9
adamc@674 10 val option_default : t ::: Type -> default t -> default (option t)
adamc@674 11 val pair_default : a ::: Type -> b ::: Type -> default a -> default b -> default (pair a b)
adamc@675 12
adamc@675 13 class awesome
adamc@675 14 val awesome_default : t ::: Type -> awesome t -> default t
adamc@675 15
adamc@675 16 val float_awesome : awesome float
adamc@674 17 end = struct
adamc@674 18 class default t = t
adamc@674 19 fun get (t ::: Type) (x : t) = x
adamc@212 20
adamc@674 21 val string_default = "Hi"
adamc@674 22 val int_default = 0
adamc@674 23
adamc@674 24 fun option_default (t ::: Type) (x : t) = Some x
adamc@674 25 fun pair_default (a ::: Type) (b ::: Type) (x : a) (y : b) = Pair (x, y)
adamc@675 26
adamc@675 27 class awesome t = t
adamc@675 28 fun awesome_default (t ::: Type) (x : t) = x
adamc@675 29
adamc@675 30 val float_awesome = 1.23
adamc@674 31 end
adamc@674 32
adamc@674 33 open M
adamc@674 34
adamc@674 35 fun default (t ::: Type) (_ : default t) : t = get
adamc@674 36 val hi : string = default
adamc@674 37 val zero : int = default
adamc@674 38 val some_zero : option int = default
adamc@674 39 val hi_zero : pair string int = default
adamc@675 40 val ott : float = default
adamc@674 41
adamc@674 42 fun frob (t ::: Type) (_ : default t) : t = default
adamc@674 43 val hi_again : string = frob
adamc@674 44 val zero_again : int = frob
adamc@674 45
adamc@674 46 fun show_option (t ::: Type) (_ : show t) : show (option t) =
adamc@674 47 mkShow (fn x =>
adamc@674 48 case x of
adamc@674 49 None => "None"
adamc@674 50 | Some y => show y)
adamc@674 51
adamc@674 52 fun show_pair (a ::: Type) (b ::: Type) (_ : show a) (_ : show b) : show (pair a b) =
adamc@674 53 mkShow (fn x =>
adamc@674 54 case x of
adamc@674 55 Pair (y, z) => "(" ^ show y ^ "," ^ show z ^ ")")
adamc@674 56
adamc@674 57 fun main () : transaction page = return <xml><body>
adamc@675 58 {[hi_again]}, {[zero_again]}, {[some_zero]}, {[hi_zero]}, {[ott]}
adamc@674 59 </body></xml>