id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1874148181,I_kwDOAMm_X85vtTtV,8123,`.rolling_exp` arguments could be clearer,5635139,open,0,,,6,2023-08-30T18:09:04Z,2023-09-01T00:25:08Z,,MEMBER,,,,"### Is your feature request related to a problem?

Currently we call `.rolling_exp` like:

```
da.rolling_exp(date=20).mean()
```

`20` refers to a ""standard"" window type — broadly ""the same average distance as a simple rolling window. That works well, and matches the `.rolling(date=20).mean()` format. 

But we also have different window types, and this makes it a bit incongruent:

```
da.rolling_exp(date=0.5, window_type=""alpha"").mean()
```

...since the `window_type` is completely changing the meaning of the value we pass to the dimension argument. A bit like someone asking ""how many apples would you like to buy"", and replying ""5"", and then separately saying ""when I said 5, I meant 5 _tonnes_"".

### Describe the solution you'd like

One option would be:

```
.rolling_exp(dptr={""alpha"": 0.5})
```

We pass a dict if we want a non-standard window type — so the value is attached to its type.

We could still have the original form for `da.rolling_exp(date=20).mean()`.

### Describe alternatives you've considered

_No response_

### Additional context

(I realize I wrote this originally, all criticism directed at me! This is based on feedback from a colleague, which on reflection I agree with.)

Unless anyone disagrees, I'll try and do this soon-ish™","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/8123/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue