Re: default instance for IsString

Markus Läll wrote:

What can go wrong when you use an overloaded string to be fromString'd into Text?

Here's an example: The author of the xml-types package provides an IsString instance for XML names, so you can conveniently represent XML names as string literals in your source code. But not every string is a valid XML name. If you mistype the literal, your program will still compile. It may even run for a while. But when someone uses your program in a way that causes that mistyped XML name literal to be resolved, your program will likely crash, unless you structured it in a way that allows that XML name literal to be wrapped in an appropriate exception handler in the IO monad. -Yitz