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From: kend@data.UUCP (Ken Dickey)
Newsgroups: comp.lang.scheme
Subject: Re: Why macros impair readability
Message-ID: <454@data.UUCP>
Date: 8 Mar 91 16:34:17 GMT
References: <9103071300.aa28959@mc.lcs.mit.edu>
Organization: Microcosm, Beaverton, OR
Lines: 24
CC: lyn@altdorf.ai.mit.EDU

In comp.lang.scheme you write:

>...  I rarely (if ever) hear
>programmers complaining that code was hard to read because it
>contained procedures, but *do* hear programmers making these kinds
>of claims about macros.

>- Lyn -

...Probably because more people are given training in what is
stylistically appropriate.  This is expressed as "the learning curve
is steep".  Once passed the curve we understand procedures and don't
have a problem reasoning about them (much).  

I feel that the same is true of syntactic transformations.  Many (most?)
people have not gone through the learning curve and write "half-baked"
macro code.  This is exacerbated when low-level macro interfaces are
used, as the "rewrite rules" are not textually apparent.  IMHO this
precisely parallels the case of going from a "high-level" language to
assembler--it takes a person knowledgeable in representation and call
pattern usage to do the appropriate thing.  The low-level is harder to
understand, harder to debug, etc.

-Ken Dickey				kend@data.uucp