> However, with this: I get how can be usefull for data directly in the code, but how this work with data that come from somwhere? If i feed a CSV with numbers,

> However, with this: I get how can be usefull for data directly in the code, but how this work with data that come from somwhere? If i feed a CSV with numbers, what happend when some is 0? The same thing that happens in any language; have a validation layer which checks whether the incoming data is zero or not. If it is, then do something appropriate (eg. print an error and halt), if not then you can safely pass if to your non-zero function. See http://existentialtype.wordpress.com/2011/03/15/boolean-blindness/ http://existentialtype.wordpress.com/2011/03/15/boolean-blin...