Re: [Scheme-reports] REPL

[Alex Shinn <alexshinn@x>]

On Wed, Nov 14, 2012 at 4:49 PM, Helmut Eller <eller.helmut@x> wrote:

Section 5.7 talks about a mysterious "top-level" environment.  Is
this any different from the (interaction-environment)?

The definition of interaction-environment states:

  The intent is that this procedure will return the environment in which

  the implementation would evaluate expressions entered by the user into

  a REPL.

Thus it is suggested, but not required, for these to

be the same.  Due to implementation differences

It's difficult to specify much about the REPL.

Regardless, interaction-environment is mutable and

thus suitable for implementing your own, portable REPL.

 

In Section 5.2 says that a REPL should permit to redefine existing
definitions.  What should happen if a record definition is redefined?
Should existing record instances be considered instances of the new
type?

Again, implementations differ here so there's not much

we can say.  Smalltalk-style class redefinition is a nice

feature, but fragile and not currently widely implemented.

-- 

Alex

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