My recollection from the last time I worked with D was that pure could be more complicated and strict than expected when using standard libraries functions, e.g

My recollection from the last time I worked with D was that pure could be more complicated and strict than expected when using standard libraries functions, e.g. using trigonometry sets hardware global state, thus impure. I don't remember if there was a good workaround to convey intent of purity despite that.