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102 lines
3.1 KiB
Text
102 lines
3.1 KiB
Text
interface Task
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exposes [Task, succeed, fail, await, map, mapFail, onFail, attempt, forever, loop, fromResult]
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imports [Effect, InternalTask]
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Task ok err fx : InternalTask.Task ok err fx
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forever : Task val err fx -> Task * err fx
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forever = \task ->
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looper = \{} ->
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task
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|> InternalTask.toEffect
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|> Effect.map
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\res ->
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when res is
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Ok _ -> Step {}
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Err e -> Done (Err e)
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Effect.loop {} looper
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|> InternalTask.fromEffect
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loop : state, (state -> Task [Step state, Done done] err fx) -> Task done err fx
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loop = \state, step ->
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looper = \current ->
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step current
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|> InternalTask.toEffect
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|> Effect.map
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\res ->
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when res is
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Ok (Step newState) -> Step newState
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Ok (Done result) -> Done (Ok result)
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Err e -> Done (Err e)
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Effect.loop state looper
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|> InternalTask.fromEffect
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succeed : ok -> Task ok * *
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succeed = \ok -> InternalTask.succeed ok
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fail : err -> Task * err *
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fail = \err -> InternalTask.fail err
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attempt : Task a b fx, (Result a b -> Task c d fx) -> Task c d fx
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attempt = \task, transform ->
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effect = Effect.after
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(InternalTask.toEffect task)
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\result ->
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when result is
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Ok ok -> transform (Ok ok) |> InternalTask.toEffect
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Err err -> transform (Err err) |> InternalTask.toEffect
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InternalTask.fromEffect effect
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await : Task a err fx, (a -> Task b err fx) -> Task b err fx
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await = \task, transform ->
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effect = Effect.after
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(InternalTask.toEffect task)
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\result ->
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when result is
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Ok a -> transform a |> InternalTask.toEffect
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Err err -> Task.fail err |> InternalTask.toEffect
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InternalTask.fromEffect effect
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onFail : Task ok a fx, (a -> Task ok b fx) -> Task ok b fx
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onFail = \task, transform ->
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effect = Effect.after
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(InternalTask.toEffect task)
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\result ->
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when result is
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Ok a -> Task.succeed a |> InternalTask.toEffect
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Err err -> transform err |> InternalTask.toEffect
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InternalTask.fromEffect effect
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map : Task a err fx, (a -> b) -> Task b err fx
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map = \task, transform ->
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effect = Effect.after
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(InternalTask.toEffect task)
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\result ->
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when result is
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Ok ok -> Task.succeed (transform ok) |> InternalTask.toEffect
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Err err -> Task.fail err |> InternalTask.toEffect
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InternalTask.fromEffect effect
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mapFail : Task ok a fx, (a -> b) -> Task ok b fx
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mapFail = \task, transform ->
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effect = Effect.after
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(InternalTask.toEffect task)
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\result ->
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when result is
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Ok ok -> Task.succeed ok |> InternalTask.toEffect
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Err err -> Task.fail (transform err) |> InternalTask.toEffect
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InternalTask.fromEffect effect
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## Use a Result among other Tasks by converting it into a Task.
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fromResult : Result ok err -> Task ok err *
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fromResult = \result ->
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when result is
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Ok ok -> succeed ok
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Err err -> fail err
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