author | wenzelm |
Thu, 09 Feb 2017 15:40:34 +0100 | |
changeset 65009 | eda9366bbfac |
parent 62505 | 9e2a65912111 |
child 78062 | edb195122938 |
permissions | -rw-r--r-- |
21394 | 1 |
(* Title: Pure/General/basics.ML |
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Author: Florian Haftmann and Makarius, TU Muenchen |
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Fundamental concepts. |
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*) |
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infix 1 |> |-> |>> ||> ||>> |
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infix 1 #> #-> #>> ##> ##>> |
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signature BASICS = |
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sig |
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(*functions*) |
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val |> : 'a * ('a -> 'b) -> 'b |
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val |-> : ('c * 'a) * ('c -> 'a -> 'b) -> 'b |
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val |>> : ('a * 'c) * ('a -> 'b) -> 'b * 'c |
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val ||> : ('c * 'a) * ('a -> 'b) -> 'c * 'b |
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val ||>> : ('c * 'a) * ('a -> 'd * 'b) -> ('c * 'd) * 'b |
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val #> : ('a -> 'b) * ('b -> 'c) -> 'a -> 'c |
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val #-> : ('a -> 'c * 'b) * ('c -> 'b -> 'd) -> 'a -> 'd |
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val #>> : ('a -> 'c * 'b) * ('c -> 'd) -> 'a -> 'd * 'b |
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val ##> : ('a -> 'c * 'b) * ('b -> 'd) -> 'a -> 'c * 'd |
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val ##>> : ('a -> 'c * 'b) * ('b -> 'e * 'd) -> 'a -> ('c * 'e) * 'd |
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val ` : ('b -> 'a) -> 'b -> 'a * 'b |
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val tap: ('b -> 'a) -> 'b -> 'b |
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(*options*) |
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val is_some: 'a option -> bool |
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val is_none: 'a option -> bool |
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val the: 'a option -> 'a |
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val these: 'a list option -> 'a list |
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val the_list: 'a option -> 'a list |
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val the_default: 'a -> 'a option -> 'a |
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val perhaps: ('a -> 'a option) -> 'a -> 'a |
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val merge_options: 'a option * 'a option -> 'a option |
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val eq_option: ('a * 'b -> bool) -> 'a option * 'b option -> bool |
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(*partiality*) |
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val try: ('a -> 'b) -> 'a -> 'b option |
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val can: ('a -> 'b) -> 'a -> bool |
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(*lists*) |
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val cons: 'a -> 'a list -> 'a list |
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val append: 'a list -> 'a list -> 'a list |
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val fold: ('a -> 'b -> 'b) -> 'a list -> 'b -> 'b |
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val fold_rev: ('a -> 'b -> 'b) -> 'a list -> 'b -> 'b |
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val fold_map: ('a -> 'b -> 'c * 'b) -> 'a list -> 'b -> 'c list * 'b |
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end; |
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structure Basics: BASICS = |
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struct |
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(* functions *) |
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(*application and structured results*) |
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fun x |> f = f x; |
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fun (x, y) |-> f = f x y; |
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fun (x, y) |>> f = (f x, y); |
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fun (x, y) ||> f = (x, f y); |
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fun (x, y) ||>> f = let val (z, y') = f y in ((x, z), y') end; |
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(*composition and structured results*) |
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fun (f #> g) x = x |> f |> g; |
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fun (f #-> g) x = x |> f |-> g; |
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fun (f #>> g) x = x |> f |>> g; |
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fun (f ##> g) x = x |> f ||> g; |
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fun (f ##>> g) x = x |> f ||>> g; |
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(*result views*) |
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fun `f = fn x => (f x, x); |
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fun tap f = fn x => (f x; x); |
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(* options *) |
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fun is_some (SOME _) = true |
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| is_some NONE = false; |
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fun is_none (SOME _) = false |
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| is_none NONE = true; |
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fun the (SOME x) = x |
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52fd62618631
prefer explicitly qualified exceptions, which is particular important for robust handlers;
wenzelm
parents:
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changeset
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| the NONE = raise Option.Option; |
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fun these (SOME x) = x |
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| these NONE = []; |
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fun the_list (SOME x) = [x] |
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| the_list NONE = [] |
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fun the_default x (SOME y) = y |
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| the_default x NONE = x; |
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fun perhaps f x = the_default x (f x); |
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fun merge_options (x, y) = if is_some x then x else y; |
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fun eq_option eq (SOME x, SOME y) = eq (x, y) |
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| eq_option _ (NONE, NONE) = true |
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| eq_option _ _ = false; |
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(* partiality *) |
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fun try f x = SOME (f x) |
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handle exn => if Exn.is_interrupt exn then Exn.reraise exn else NONE; |
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fun can f x = is_some (try f x); |
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(* lists *) |
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fun cons x xs = x :: xs; |
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fun append xs ys = xs @ ys; |
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fun fold _ [] y = y |
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| fold f (x :: xs) y = fold f xs (f x y); |
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fun fold_rev _ [] y = y |
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| fold_rev f (x :: xs) y = f x (fold_rev f xs y); |
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fun fold_map _ [] y = ([], y) |
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| fold_map f (x :: xs) y = |
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let |
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val (x', y') = f x y; |
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val (xs', y'') = fold_map f xs y'; |
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in (x' :: xs', y'') end; |
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end; |
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open Basics; |