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78 lines
2 KiB
Text
78 lines
2 KiB
Text
interface Task
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exposes [Task, succeed, fail, after, map, putLine, putInt, getInt, forever, loop]
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imports [pf.Effect]
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Task ok err : Effect.Effect (Result ok err)
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forever : Task val err -> Task * err
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forever = \task ->
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looper = \{} ->
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task
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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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loop : state, (state -> Task [Step state, Done done] err) -> Task done err
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loop = \state, step ->
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looper = \current ->
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step current
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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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succeed : val -> Task val *
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succeed = \val ->
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Effect.always (Ok val)
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fail : err -> Task * err
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fail = \val ->
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Effect.always (Err val)
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after : Task a err, (a -> Task b err) -> Task b err
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after = \effect, transform ->
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Effect.after
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effect
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\result ->
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when result is
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Ok a -> transform a
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Err err -> Task.fail err
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map : Task a err, (a -> b) -> Task b err
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map = \effect, transform ->
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Effect.map
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effect
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\result ->
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when result is
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Ok a -> Ok (transform a)
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Err err -> Err err
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putLine : Str -> Task {} *
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putLine = \line -> Effect.map (Effect.putLine line) (\_ -> Ok {})
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putInt : I64 -> Task {} *
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putInt = \line -> Effect.map (Effect.putInt line) (\_ -> Ok {})
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getInt : Task I64 []
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getInt =
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Effect.after
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Effect.getInt
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\{ isError, value } ->
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if
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isError
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then
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# when errorCode is
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# # A -> Task.fail InvalidCharacter
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# # B -> Task.fail IOError
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# _ ->
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Task.succeed -1
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else
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Task.succeed value
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