Re: [stack] the concatenative wikipedia article

> So would the category of all languages that use 'car' and 'cdr' to
>
> take the head and tail of a list. Such a category would basically mean
> Lisp and derivatives, but the definition of the category itself
> wouldn't let us say anything useful. I think that's the danger with
> your definition: It allows the things we want to allow, but doesn't
> let us say anything about them.
>

bad example: car and cdr talk about semantics not syntax.

but you are right: we want positive statements, not negative.
in true leo brouwer style:

'let's be constructive!'

> Enchilada is what I'd call a postfix term rewriting language. I don't
> think I'd consider it concatenative due to the presence of lambdas.
> Discussions in the past have indicated that lexical scope and
> substitution are not compatible with concatenativity. For example,
> given the expression '{a b=a b +}', I cannot define 'f' to be 'b +'
> and then say '{a b=a b +} == {a b=a f}'.
>
there is a catch:

a lambda in enchilada is an unary (monadic) operator that is also a  
atomic term.
as a consequence, you can't substitute expressions that are within the  
{scope} of a lambda.

also, definitions shouldn't contain free variables (or symbols as they  
are called in enchilada)

> - John

- robbert.