Re: learning languages [Was: Re: Y Store now C++]

["Christopher Barber" <address@hidden>]

> DrScheme is a step in this direction.  We recognized that textbooks do
> not present languages as all-or-nothing deals, so why should
> programming languages?  We therefore built a series of language
> "levels" that grow semantically more complex.  In the more restrictive
> language levels, the environment can place certain restrictions that
> catch errors sooner.  (For instance, in a language level without
> first-class functions, certain syntactic patterns that would be
> syntactically legal but lead to erroneous programs in full Scheme can
> be rejected statically.)

Interesting.  So how many levels are there and what did you put in each
level?

- Christopher