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爲什麼我不能將None添加到System.Collections.Generic.Dictionary的Option？這是Mono中的預期行爲還是錯誤？F＃字典選項
F# Interactive for F# 3.1 (Open Source Edition)
Freely distributed under the Apache 2.0 Open Source License
For help type #help;;
> open System.Collections.Generic;;
> let d1 = new Dictionary<int option, int>();;
val d1 : Dictionary<int option,int> = dict []
> d1.Add(None, 1);;
System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.ThrowHelper.ThrowArgumentNullException (ExceptionArgument argument) in <filename unknown>:line 0
at System.Collections.Generic.Dictionary`2[TKey,TValue].Insert (System.Collections.Generic.TKey key, System.Collections.Generic.TValue value, Boolean add) in <filename unknown>:line 0
at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (System.Collections.Generic.TKey key, System.Collections.Generic.TValue value) in <filename unknown>:line 0
at <StartupCode$FSI_0004>[email protected]() in <filename unknown>:line 0
at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) in <filename unknown>:line 0
Stopped due to error
> d1.Add(Some 10, 1);;
val it : unit =()
我使用的是單聲道在OS X
$ mono --version
Mono JIT compiler version 4.2.0 (Stable 4.2.0.179/a224653 Tue Oct 6 11:28:25 PDT 2015)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: normal
SIGSEGV: altstack
Notification: kqueue
Architecture: amd64
Disabled: none
Misc: softdebug
LLVM: supported, not enabled.
GC: sgen
嘗試'讓d1 = new Dictionary（HashIdentity.Structural）'。 –
ildjarn
它不起作用。 –
@ Ming-Tang不幸的是，正如凱文所說，這是理想的行爲。定期'字典<_,_>'不接受'空'作爲關鍵。另一方面，F＃的地圖<_,_>'按預期工作，但我知道它可能不是一個合適的替代品。 –