[plt-scheme] Re: Is R6RS useless for PLT?

On 18-Nov-08, at 9:48 AM, Shriram Krishnamurthi wrote:

> Out of curiosity, how many Perl implementations do you routinely port
> between?  Or Ruby implementations?  Or Tcl implementations?

Shriram, you are neglecting the fact that there are many (as in  
*many*) implementations of Scheme.  This diversity is not gratuitous.   
Each implementation covers some niche of the programming spectrum.   
Some Schemes are well suited for teaching programming, some are geared  
towards fast compilation, some towards fast execution, some target  
embedded systems, some interoperate well with other languages (C,  
Java, .NET, ...), some are easily ported to new platforms, some have  
nice debugging environments, some have nice documentation, etc.  No  
single implementation does it all.

The thing is that a piece of software is constantly in evolution.  It  
may start small with a single objective, but subsequently grow with a  
change of focus, and thus a change of requirements from the Scheme  
system.  That is why portability of the source code is important.  It  
allows the developer to switch between Scheme implementations as the  
requirements of the software evolve, or as the developer discovers  
bugs and weaknesses in the Scheme he initially chose.

The diversity of Scheme implementations should be viewed as one of the  
strengths of Scheme, not a weakness.

Marc