Can this be simplified as:
```el
(sp-pair "{" nil :post-handlers
         '(((lambda (&rest _ignored)
              (prelude-smart-open-line-above)) "RET")))
```

@bbatsov I think this should be the default for all programming modes, it's also how editors like textmate and sublime  handle curly braces, initially after hitting <kbd>{</kbd>, the cursor is in the middle:
```
{|}
```
Then, hit return:
```
{
    |
}
```
The close brace should be on the third line with the cursor in the middle line and indented.