These languages are all looking like crafted , so that they run no existing code. If the language is 'more' like Scheme, as the author says, there is enough dif

These languages are all looking like crafted , so that they run no existing code. If the language is 'more' like Scheme, as the author says, there is enough difference built in, so that no Scheme program runs. Imagine being directly able to use one of the countless Scheme books/libraries/... to experiment with it. To work with something like SICP one really needs only a tiny Scheme...