Re: Add internal definitions to derived forms

[Lassi Kortela]

> Not quite. Guile extends the lambda body (and by extension let-forms) to allow 
> mixed definitions and expressions:
>
> (lambda ()
>    (display "Heippa!")
>    (define routsi #t)
>    (and (read) routsi))
>
> which expands to, more or less, a letrec*. All in accordance to the paper 
> fixing letrec(reloaded).
>
> Thus saying that the cond clause body is like a lambda body is probably the 
> simplest way to express it.

R7RS defines the syntax of `let` et.al. as follows (section 3.5):

(let (<binding spec>*) <tail body>)

Where:

<tail body> = <definition>* <tail sequence>
<tail sequence> = <expression>* <tail expression>

So their definition of lambda:

(lambda <formals> <definition>* <expression>* <tail expression>)

could be abbreviated:

(lambda <formals> <tail body>)

I haven't read "Fixing letrec" but it looks like Guile intents to 
redefine <tail body> as follows:

<tail body> = <definition-or-expression>* <tail expression>
<definition-or-expression>* = <definition> | <expression>

R6RS appears to use <tail body> in the same sense as R7RS.