30 lines
753 B
Forth
30 lines
753 B
Forth
namespace Sanchime.Monads
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module Test =
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let reader_example () =
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let cache (Reader(f)) = (Reader (fun (v1, v2) ->
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match v1 with
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| None -> f v2
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| Some v -> v))
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let read s n = reader {
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printfn "读取：%s" s
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return n
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}
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let m = reader {
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let! a = cache <| read "A" 1
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let! b = cache <| read "B" 2
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let! c = read "C" 3
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return a + b + c
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}
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let (Reader f) = m
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f ((None, ()), ((None, ()), ((), ()))) |> ignore
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f ((Some 1, ()), ((None, ()), ((), ()))) |> ignore
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f ((None, ()), ((Some 2, ()), ((), ()))) |> ignore
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f ((Some 1, ()), ((Some 2, ()), ((), ()))) |> ignore
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