Re: MzScheme and SML

[John Clements <clements@cs.rice.edu>]

>
>This interests me.  Here is a quote from Andrew Appel of Princeton, one of
>SML's designers, commenting on SML's lack of macros:
>
>     This is clearly an advantage, not a disadvantage.  For the programmer
>     to have to calculate a string-to-string rewrite of the program before
>     any semantic analysis invites problems of the worst kind.  Where macros
>     are used to attain the effect of in-line expansion of functions, they
>     are doing something that should be done by an optimizing compiler.
>     Where macros are used to attain call-by-name, the effect can be
>     acheived by passing a suspension as an argument; in ML this is written
>     with the syntax fn()=> which though admittedly ugly is fairly concise,
>     and is better than tolerating the semantic havoc wrought by macros.
>
>     [From "A critique of Standard ML", 1992]

One other point, perhaps already noted: the paragraph reads well, but 
dodges the question: his specific criticism of macros is confined to 
the phrase "semantic havoc"; the rest of the paragraph is devoted to 
explaining how to work around them.  I've written many paragraphs 
like this myself, and they've generally arisen when I am unable to 
come up with a more detailed criticism.

Of course, I'm reading this paragraph out of context; the surrounding 
text may address these issues more precisely.

john clements