Why can't we declare var a = new List at class level?

Question

I know we cannot do this at class level but at method level we can always do this.

var myList=new List // or something else like this
<         


        

Answer 1

There are technical issues with implementing this feature. The common cases seem simple but the tougher cases (e.g., fields referencing other fields in chains or cycles, expressions which contain anonymous types) are not.

See Eric Lippert's blog for an in-depth explanation: Why no var on fields?