Safe versus unsafe arrays

[Bradley Lucier]

I have come to regret the choice that initially, to hypothetically speed 
array operations, the parameter specialized-array-default-safe? is not 
#t, which would guarantee run-time checks of array getter and setter 
arguments.  It's not a good look when by default, a library crashes the 
Scheme system when the programmer makes a mistake.

The SRFI document implies, but does not explicitly say, those checks are 
not in place when an array is created and 
specialized-array-default-safe? is #f.

I'm going to do some performance tests with Gambit's implementation of 
SRFI 231, which tracks the sample implementation.  If the performance 
hit is not large, I may set Gambit's implementation to start with safe 
arrays by default.

In a Gambit PR Marc Feeley commented "I would have created 2 variants of 
the SRFI: (srfi 231) and (srfi 231 unsafe) so that ... by default you 
get the type checks ..."

An interesting idea that would imply a compile-time choice of safe or 
unsafe arrays instead of a runtime choice at array-creation time.

Brad