[MLton-commit] r4927

[Vesa Karvonen]

Reorganized public files.
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D   mltonlib/trunk/com/ssh/extended-basis/unstable/public/promise.sig

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Deleted: mltonlib/trunk/com/ssh/extended-basis/unstable/public/promise.sig
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--- mltonlib/trunk/com/ssh/extended-basis/unstable/public/promise.sig	2006-12-10 19:10:42 UTC (rev 4926)
+++ mltonlib/trunk/com/ssh/extended-basis/unstable/public/promise.sig	2006-12-10 19:10:49 UTC (rev 4927)
@@ -1,79 +0,0 @@
-(* Copyright (C) 2006 SSH Communications Security, Helsinki, Finland
- *
- * This code is released under the MLton license, a BSD-style license.
- * See the LICENSE file or http://mlton.org/License for details.
- *)
-
-(**
- * Lazy promises.
- *
- * The design is based on [http://srfi.schemers.org/srfi-45/ SRFI-45]
- * ``Primitives for Expressing Iterative Lazy Algorithms'' by André van
- * Tonder.
- *
- * The general recipe to express lazy algorithms is to
- * - wrap all constructors with {delay (fn () => ...)},
- * - apply {force} to arguments of destructors, and
- * - wrap function bodies with {lazy (fn () => ...)}.
- *)
-signature PROMISE = sig
-   type 'a t
-   (** The abstract type of promises. *)
-
-   val delay : 'a Thunk.t -> 'a t
-   (**
-    * Takes a thunk of type {'a thunk} and returns a promise of type
-    * {'a t} which at some point in the future may be asked (by the
-    * {force} procedure) to evaluate the thunk and deliver the
-    * resulting value.
-    *)
-
-   val eager : 'a -> 'a t
-   (**
-    * Takes an argument of type {'a} and returns a promise of type
-    * {'a t}.  As opposed to {delay}, the argument is evaluated eagerly.
-    *
-    * Semantically, writing
-    *
-    *> eager expression
-    *
-    * is equivalent to writing
-    *
-    *> let val value = expression in delay (fn () => value) end
-    *
-    * However, the former is more efficient since it does not require
-    * unnecessary creation and evaluation of thunks.  We also have the
-    * equivalence
-    *
-    *> delay (fn () => expression) = lazy (eager expression)
-    *
-    * assuming that evaluation of the expression does not raise an
-    * exception.
-    *)
-
-   val force : 'a t -> 'a
-   (**
-    * Takes a promise of type {'a t} and returns a value of type {'a}
-    * as follows: If a value of type {'a} has been computed for the
-    * promise, this value is returned.  Otherwise, the promise is first
-    * evaluated, then overwritten by the obtained promise or value, and
-    * then force is again applied (iteratively) to the promise.
-    *)
-
-   val lazy : 'a t Thunk.t -> 'a t
-   (**
-    * Takes a thunk returning a promise of type {'a t} and returns a
-    * promise of type {'a t} which at some point in the future may be
-    * asked (by the {force} procedure) to evaluate the thunk and
-    * deliver the resulting promise.
-    *)
-
-   val toThunk : 'a t -> 'a Thunk.t
-   (**
-    * Converts a promise into a thunk.  This can be useful for working
-    * around the value restriction, for example.
-    *)
-
-   val Y : 'a t Tie.t
-   (** Fixpoint tier for promises. *)
-end