What about [function composition](https://en.wikipedia.org/wiki/Function_composition)?  [Haskell](http://www.haskell.org/haskellwiki/Function_composition) uses dot for this, as in 

```
g . f
```

I got to that by wondering were there such an operator as proposed, besides making heavy use of its intended purpose, how might I overload it?  The first thing that springs to mind is functional composition and application.  The fundamental idea of a matrix is as a function on vectors; matrix-matrix multiplication is defined subsequently by associativity.  If I had arbitrary compatible functions f and g and an argument x, would I like to write 

```python
f @ x
```
for 

```python
f (x)
```
and 
```python
g @ f
``` 
for 
```python
lambda x: g (f (x))
```
?  Maybe not the former so much but the latter definitely.