lambda cannot express letrec.
Macro-expanding the top-level into a letrec and then showing its
semantics would, again, make it harder to follow along with traces of
a reduction sequence.
(Also, as I understand it, the jury is still out on whether or not the
top-level of a module is the same as a lambda. See Kent's earlier
formal comment.)
Robby
On 3/14/07, AndrevanTonder <andre_at_het.brown.edu> wrote:
> ---
> This message is a formal comment which was submitted to formal-comment_at_r6rs.org, following the requirements described at: http://www.r6rs.org/process.html
> ---
> Name : Andre van Tonder
> Email : andre at het.brown.edu
> Type : simplification
> Priority : medium
> Component : formal semantics
> Version : 5.92
> Pages : 71-73
> Dependencies: None
>
> Summary:
> --------
>
> Formal semantics of library toplevel is meaningless, unnecessary and clashes
> with the description in the body of the document. It should be removed.
>
> Description:
> ------------
>
> The formal description of the library semantics unnecessarily
> adds significant volume to the formal semantics. It is also inconsistent
> with the informal description of the library semantics and "expansion process"
> described in the body of the document.
>
> According to the description in the text, a library residualizes to the
> equivalent of a LETREC* expression. Therefore
>
> 1) Its semantics can be reduced to that of LAMBDA.
> 2) Because of (1), the formal semantics for libraries is redundant
> and should be removed.
> 3) Even worse, the formal semantics for libraries is meaningless.
> It purports to give a semantics to DEFINE forms. However, an
> expanded library contains no DEFINEs, just a LETREC*.
>
> Suggestion:
> -----------
>
> Remove the formal semantics of libraries. It should be sufficient
> to include a note that since libraries expand to LETREC*, their semantics can
> be understood in terms of LAMBDA.
>
>
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>
Received on Thu Mar 15 2007 - 08:51:57 UTC