Dear Alexander,
thanks for the link again ! (
http://dl.acm.org/citation.cfm?id=281508.281540 )
Indeed it is not surprising that some features of GAP seem unusual.
Just let us forget GAP for a moment and think in general about one of my
previous questions:
What positive or negative implications for a language e.g. 'python'
would have a silently failed action?
Is it worthwhile and possible to change the behaviour of the language or
not?
Best,
Jakob
( Яков )
P.S. I'm posting some observations which seems unusual to me promptly,
because as soon as I get adopted to GAP
I wouldn't even notice. In general some implications of (historically
grown) functionality are not automatically 'useful' or 'unfavourable',
e.g. the financial system is evolved over time but I hope you agree that
it also has some serious problems.
Am 10.03.2012 19:30, schrieb Alexander Konovalov:
Dear Jakob,
On 9 Mar 2012, at 14:52, kroeker wrote:
...
there is no way to "lock" an operation, [..] it would also cause problems
Let for now assume that it is not necessary to lock operations. Then in my
opinion a user should get at least a warning that locking is not possible when
trying it.
By the way, It shouldn't be possible to lock existing read-only operations, so
it is not obvious to me that locking an operation would cause problems a priori.
It also seems that other functionality in GAP has similar behaviour which is
unusual from my point of view:
actions fail without a warning, e.g. calling an attribute setter twice with
different values (the second call has no effect)
GAP may be regarded as a problem-oriented language designed to be a platform
for implementing mathematical (mostly discrete) algorithms, and it has rather
unique object-oriented features invented to model mathematical objects: for
example, objects that learn during their lifetime and change their type in the
process, and dynamic polymorphism (that is, method selection based on current
type of all arguments). So it's not surprising that from the beginning some of
its features may seem unusual.
There is a paper "The GAP 4 type system: organising algebraic algorithms" by
Steve Linton and Thomas Breuer in ISSAC'98 proceedings available here:
http://dl.acm.org/citation.cfm?id=281508.281540
which may give more details about the reasoning behind GAP design principles,
in addition to the GAP manual.
Best wishes,
Alexander
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