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1 point by almkglor 6011 days ago | link | parent

Personally, I'm rather squeamish about letting 'eval be redefined. Because the redefined 'eval will not be consistently used.

Perhaps it's better to just define a top-level which preprocesses the code before passing it to 'eval?



2 points by eds 6011 days ago | link

That could be accomplished by redefining 'arc-eval rather than 'eval. 'arc-eval is used internally for evaluating top-level forms but not really anything else since it isn't exposed to arc, whereas 'eval could be used by arbitrary arc code. If you want to redefine the top-level evaluation function, than maybe what you want is some way to influence the results of 'arc-eval.

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1 point by almkglor 6011 days ago | link

So much easier:

  (def mytl ()
    (pr "arc> ")
    (eval (my-transformation (read)))
    (mytl))

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2 points by eds 6011 days ago | link

I guess I misunderstood your intention. I thought you wanted to be able to redefine the existing toplevel used by the arc interpreter itself, not define a completely new toplevel to be used in user code... (and yes, the latter is quite trivial).

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1 point by almkglor 6011 days ago | link

> I thought you wanted to be able to redefine the existing toplevel used by the arc interpreter itself

As opposed to emulating the existing toplevel in user code?

Allowing a redefinition of 'eval to work on the REPL will probably be OK, but still, there would be an impedance mismatch with functions that were defined before 'eval was redefined.

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