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Implementing generic IEnumerator
f#

> { new IEnumerator<int> with Reset() = () and MoveNext() = true and get_Current
() = 0 and Dispose() = () };;

{ new IEnumerator<int> with Reset() = () and MoveNext() = true and get_Current
() = 0 and Dispose() = () };;
-------------------------------------------------------------------^^^^^^^^^^^
^

stdin(14,67): error: FS0001: This expression has type
obj
but is here used with type
int
stopped due to error

I've been having problems with implementing IEnumerator (the generic version) and isolated the problem and it can be seen above from fsi. Does anyone have any thoughts as to why this fails? (the underlining occurs from the g in get_current to the ( after the t.)

.

IEnumerator<T> extends the non-generic IEnumerator. This means there are two get_Current methods to implement, with different return types, which means you should implement the non-generic interface explicitly:

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open System.Collections.Generic

let x = { new IEnumerator<int> 
            with get_Current() = 0 
          interface System.Collections.IEnumerator
            with get_Current() = box 0 
            and  Reset() = () 
            and  MoveNext() = true 
          interface System.IDisposable
            with Dispose() = () 
            };;

There are many examples in the implementation of the IEnumerable module (ienumerable.fs) in the distribution.

cheers,

don

By on 9/23/2006 5:54 AM ()

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