17 lines
1.1 KiB
TypeScript
17 lines
1.1 KiB
TypeScript
// Copyright 2016-2017, Pulumi Corporation. All rights reserved.
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// Computed represents a variable whose value may not yet be known. Not only may it not be known, but it may or
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// may not become known at some point in the future. The program should not depend on concrete values for correctness,
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// and should only use the `map` function to create derived dataflow values. For example, a logical value `v` may be
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// transformed by `v+1`, and that resulting computed value may be then plugged into places expecting computed values
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// (and so on and so forth). Unlike promises, the values are guaranteed to *never* resolve under some circumstances,
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// such as during planning, so forward progress must not depend on resolution.
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export interface Computed<T> {
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// mapValue attaches a callback for the resolution of a computed value, and returns a newly computed value.
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mapValue<U>(callback: (v: T) => MaybeComputed<U>): Computed<U>;
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}
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// MaybeComputed is one of: a T, a computed of T (whose value may not yet be known), or a promise of T.
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export type MaybeComputed<T> = T | Computed<T> | Promise<T>;
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