ramda/ramda — pull request #471 by benperez (2014-10-22 04:08:09+00:00)
Title: Add R.scanl

Found myself wanting this functionality recently. It's nice for building up a collection of intermediate values while reducing. Here's an example of where one could be applying an increasingly stringent set of filters to an ElasticSearch or MongoDB style query:
```javascript
> var location = {state: 'CA', city: 'San Francisco', zip: 94108};
> R.scanl(R.mixin, {}, [{state: trans.state}, {city: trans.city}, {zip: trans.zip}]);
<
[
{}, // no filter
{"state": "CA"}, // just state
{"state": "CA", "city": "San Francisco"}, // city and state
{"state": "CA", "city": "San Francisco", "zip": 94108} // city, state, and zip
]

```
Inspired by Haskell [scanl](http://en.wikibooks.org/wiki/Haskell/List_processing#Scans)