author | blanchet |
Wed, 04 Mar 2009 10:45:52 +0100 | |
changeset 30240 | 5b25fee0362c |
parent 29564 | f8b933a62151 |
child 31427 | 5a07cc86675d |
permissions | -rw-r--r-- |
23962 | 1 |
(* Title: Pure/ML-Systems/exn.ML |
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Author: Makarius |
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Extra support for exceptions. |
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*) |
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signature EXN = |
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sig |
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datatype 'a result = Exn of exn | Result of 'a |
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val get_result: 'a result -> 'a option |
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val get_exn: 'a result -> exn option |
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val capture: ('a -> 'b) -> 'a -> 'b result |
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val release: 'a result -> 'a |
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exception Interrupt |
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28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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exception EXCEPTIONS of exn list |
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val release_all: 'a result list -> 'a list |
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val release_first: 'a result list -> 'a list |
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end; |
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structure Exn: EXN = |
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struct |
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(* runtime exceptions as values *) |
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datatype 'a result = |
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Result of 'a | |
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Exn of exn; |
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fun get_result (Result x) = SOME x |
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| get_result _ = NONE; |
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fun get_exn (Exn exn) = SOME exn |
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| get_exn _ = NONE; |
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fun capture f x = Result (f x) handle e => Exn e; |
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fun release (Result y) = y |
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| release (Exn e) = raise e; |
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28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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(* interrupt and nested exceptions *) |
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exception Interrupt = Interrupt; |
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28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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exception EXCEPTIONS of exn list; |
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|
28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
46 |
fun plain_exns (Result _) = [] |
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
47 |
| plain_exns (Exn Interrupt) = [] |
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
48 |
| plain_exns (Exn (EXCEPTIONS exns)) = List.concat (map (plain_exns o Exn) exns) |
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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| plain_exns (Exn exn) = [exn]; |
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fun release_all results = |
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if List.all (fn Result _ => true | _ => false) results |
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then map (fn Result x => x) results |
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else |
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28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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(case List.concat (map plain_exns results) of |
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[] => raise Interrupt |
28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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| exns => raise EXCEPTIONS exns); |
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fun release_first results = release_all results |
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28459
f6a4d913cfb1
simplified Exn.EXCEPTIONS, flatten nested occurrences;
wenzelm
parents:
28444
diff
changeset
|
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handle EXCEPTIONS (exn :: _) => raise exn; |
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end; |