Regarding Backus' Commentary on von Neumann-style Programming
Reading the quote literally without the interpolated interpretation, I think what Backus is saying is that a powerful language is one which makes no distinction between expressions and statements.
That is, where all statements are also expressions, like a functional language.
I don't think Backus was claiming that an &quot;all statement&quot; language - the meaning of which is not entirely clear in this context - would be powerful or even feasible. Rather, he is claiming that the existence of certain statements that cannot be analysed as expressions, is a defect in language design.