I can divide a float by an integer

> 2.4 / 3

0.7999999999999999

but why can I not do this?

< 2.4 / (length [1,2,3])

<interactive>:288:1-22: error:
* No instance for (Fractional Int) arising from a use of `/'
* In the expression: 2.4 / (length [1, 2, 3])