Re: [Pharo-dev] [squeak-dev] Float hierarchy for 64-bit Spur
Hi Tobias, On Fri, Nov 21, 2014 at 4:51 AM, Tobias Pape <Das.Linux@gmx.de> wrote:
Hi,
On 21.11.2014, at 13:44, Bert Freudenberg <bert@freudenbergs.de> wrote:
On 21.11.2014, at 13:29, J. Vuletich (mail lists) < juanlists@jvuletich.org> wrote:
Quoting Bert Freudenberg <bert@freudenbergs.de>:
I'd suggest BoxedDouble and ImmediateDouble as names for the concrete
subclasses (*). Names do mean something. (**)
You're right about the FloatArray confusion. However, note that the
IEEE standard calls it single and double. It's only C using "float" to mean "single precision".
I'd name the abstract superclass Float, for readability, and the
isFloat test etc. Also: "Float pi" reads a lot nicer than anything else. I don't see the need for having a deep LimitedPrecisionReal - Float - BoxedDouble/ImmediateDouble deep hierarchy now.
If we ever add single-precision floats, we should name them
BoxedSingle and ImmediateSingle. At that point we might want a Single superclass and a LimitedPrecisionReal supersuperclass, but we can cross that bridge when we get there.
- Bert -
(*) Since we're not going to see the class names often, we could even
spell it out as BoxedDoublePrecisionFloat and ImmediateDoublePrecisionFloat. Only half joking. It would make the relation to the abstract Float very clear.
(**) We could also try to make the names googleable. I was surprised
to not get a good hit for "boxed immediate". Only "boxed unboxed" finds it. Maybe there are two better words?
I very much agree with Bert. But I'd suggest SmallDouble instead of ImmediateDouble for consistency with SmallInteger.
Then it would have to be LargeDouble for consistency with LargeInteger, too. Which I don't find compelling.
Also, with the 64 bit format we get many more immediate objects. There already are immediate integers and characters, floats will be the third, there could be more, like immediate points. For those, the small/large distinction does not make sense.
Maybe Eliot's idea of keeping "Float" in the name was best, but instead of "small" use "immediate":
Float - BoxedFloat - ImmediateFloat
A Float is either a BoxedFloat or an ImmediateFloat, depending on the magnitude of its exponent.
I don't like the idea of putting a VM/Storage detail into the Class name. The running system itself does not care about whether Floats or Integers are boxed or immediate.
I disagree. I think at least Smalltalk-80 has a philosophy of lifting as much out of the VM into the system, and hiding it from clients via encapsulation. So unlike many other VMs the compiler is in the system, the system explicitly separates SmallInteger, LargePositiveInteger and LargeNegativeInteger and implements large integer arithmetic with Smalltalk code that uses SmallIntegers. Note that the primitives are an optional extra optimization that the VM does not need to implement. So for me it is in keeping with the current system to use BoxedFloat and SmallFloat or BoxedDouble and SmallDouble. This lifting things up provides us with an extremely malleable system. Pushing things down into the VM does the opposite. For example in RSqueakVM (aka SPy) there is no immediate
Integer whatsoever. Yes, tagged ints are read during image startup but they aren't subsequently represented as immediates or tagged ints after that.
Well because it's implemented above RPython I guess it is using Python's bignum code directly. That's fine but its a bit of a cheat.
Just as input, in the Racket language and other Schemes, the equivalent to our SmallInterger/LargeInteger is fixnum/bignum and for floats they have flonums and "extflonums" (80bit).
Best -Tobias
thanks -- best, Eliot
Hi Eliot On 21.11.2014, at 19:06, Eliot Miranda <eliot.miranda@gmail.com> wrote:
Hi Tobias,
On Fri, Nov 21, 2014 at 4:51 AM, Tobias Pape <Das.Linux@gmx.de> wrote:
Hi,
On 21.11.2014, at 13:44, Bert Freudenberg <bert@freudenbergs.de> wrote:
On 21.11.2014, at 13:29, J. Vuletich (mail lists) < juanlists@jvuletich.org> wrote:
Quoting Bert Freudenberg <bert@freudenbergs.de>:
I'd suggest BoxedDouble and ImmediateDouble as names for the concrete
subclasses (*). Names do mean something. (**)
You're right about the FloatArray confusion. However, note that the
IEEE standard calls it single and double. It's only C using "float" to mean "single precision".
I'd name the abstract superclass Float, for readability, and the
isFloat test etc. Also: "Float pi" reads a lot nicer than anything else. I don't see the need for having a deep LimitedPrecisionReal - Float - BoxedDouble/ImmediateDouble deep hierarchy now.
If we ever add single-precision floats, we should name them
BoxedSingle and ImmediateSingle. At that point we might want a Single superclass and a LimitedPrecisionReal supersuperclass, but we can cross that bridge when we get there.
- Bert -
(*) Since we're not going to see the class names often, we could even
spell it out as BoxedDoublePrecisionFloat and ImmediateDoublePrecisionFloat. Only half joking. It would make the relation to the abstract Float very clear.
(**) We could also try to make the names googleable. I was surprised
to not get a good hit for "boxed immediate". Only "boxed unboxed" finds it. Maybe there are two better words?
I very much agree with Bert. But I'd suggest SmallDouble instead of ImmediateDouble for consistency with SmallInteger.
Then it would have to be LargeDouble for consistency with LargeInteger, too. Which I don't find compelling.
Also, with the 64 bit format we get many more immediate objects. There already are immediate integers and characters, floats will be the third, there could be more, like immediate points. For those, the small/large distinction does not make sense.
Maybe Eliot's idea of keeping "Float" in the name was best, but instead of "small" use "immediate":
Float - BoxedFloat - ImmediateFloat
A Float is either a BoxedFloat or an ImmediateFloat, depending on the magnitude of its exponent.
I don't like the idea of putting a VM/Storage detail into the Class name. The running system itself does not care about whether Floats or Integers are boxed or immediate.
I disagree. I think at least Smalltalk-80 has a philosophy of lifting as much out of the VM into the system, and hiding it from clients via encapsulation. So unlike many other VMs the compiler is in the system, the system explicitly separates SmallInteger, LargePositiveInteger and LargeNegativeInteger and implements large integer arithmetic with Smalltalk code that uses SmallIntegers. Note that the primitives are an optional extra optimization that the VM does not need to implement. So for me it is in keeping with the current system to use BoxedFloat and SmallFloat or BoxedDouble and SmallDouble.
This lifting things up provides us with an extremely malleable system. Pushing things down into the VM does the opposite.
I can understand. It is however a tradeoff between abstraction and malleability. I'd rather see everything done in Smalltalk. Yet primitives not exposing its innards. I think I just can't have the cake and have it, too.
For example in RSqueakVM (aka SPy) there is no immediate
Integer whatsoever. Yes, tagged ints are read during image startup but they aren't subsequently represented as immediates or tagged ints after that.
Well because it's implemented above RPython I guess it is using Python's bignum code directly. That's fine but its a bit of a cheat.
I was talking of SmallInts here. There is no bignum code involved. On the RPython side, SmallIntegers are just objects that have a field that is not accessible from Smalltalk but keeps a machine-word integer.
Just as input, in the Racket language and other Schemes, the equivalent to our SmallInterger/LargeInteger is fixnum/bignum and for floats they have flonums and "extflonums" (80bit).
Best -Tobias
Hi Tobias, On Fri, Nov 21, 2014 at 10:52 AM, Tobias Pape <Das.Linux@gmx.de> wrote:
Hi Eliot
On 21.11.2014, at 19:06, Eliot Miranda <eliot.miranda@gmail.com> wrote:
Hi Tobias,
On Fri, Nov 21, 2014 at 4:51 AM, Tobias Pape <Das.Linux@gmx.de> wrote:
Hi,
On 21.11.2014, at 13:44, Bert Freudenberg <bert@freudenbergs.de>
wrote:
On 21.11.2014, at 13:29, J. Vuletich (mail lists) < juanlists@jvuletich.org> wrote:
Quoting Bert Freudenberg <bert@freudenbergs.de>:
I'd suggest BoxedDouble and ImmediateDouble as names for the
concrete
subclasses (*). Names do mean something. (**)
You're right about the FloatArray confusion. However, note that the
IEEE standard calls it single and double. It's only C using "float" to mean "single precision".
I'd name the abstract superclass Float, for readability, and the
isFloat test etc. Also: "Float pi" reads a lot nicer than anything else. I don't see the need for having a deep LimitedPrecisionReal - Float - BoxedDouble/ImmediateDouble deep hierarchy now.
If we ever add single-precision floats, we should name them
BoxedSingle and ImmediateSingle. At that point we might want a Single superclass and a LimitedPrecisionReal supersuperclass, but we can cross that bridge when we get there.
- Bert -
(*) Since we're not going to see the class names often, we could
even spell it out as BoxedDoublePrecisionFloat and ImmediateDoublePrecisionFloat. Only half joking. It would make the relation to the abstract Float very clear.
(**) We could also try to make the names googleable. I was
surprised to not get a good hit for "boxed immediate". Only "boxed unboxed" finds it. Maybe there are two better words?
I very much agree with Bert. But I'd suggest SmallDouble instead of ImmediateDouble for consistency with SmallInteger.
Then it would have to be LargeDouble for consistency with LargeInteger, too. Which I don't find compelling.
Also, with the 64 bit format we get many more immediate objects. There already are immediate integers and characters, floats will be the third, there could be more, like immediate points. For those, the small/large distinction does not make sense.
Maybe Eliot's idea of keeping "Float" in the name was best, but instead of "small" use "immediate":
Float - BoxedFloat - ImmediateFloat
A Float is either a BoxedFloat or an ImmediateFloat, depending on the magnitude of its exponent.
I don't like the idea of putting a VM/Storage detail into the Class name. The running system itself does not care about whether Floats or Integers are boxed or immediate.
I disagree. I think at least Smalltalk-80 has a philosophy of lifting as much out of the VM into the system, and hiding it from clients via encapsulation. So unlike many other VMs the compiler is in the system, the system explicitly separates SmallInteger, LargePositiveInteger and LargeNegativeInteger and implements large integer arithmetic with Smalltalk code that uses SmallIntegers. Note that the primitives are an optional extra optimization that the VM does not need to implement. So for me it is in keeping with the current system to use BoxedFloat and SmallFloat or BoxedDouble and SmallDouble.
This lifting things up provides us with an extremely malleable system. Pushing things down into the VM does the opposite.
I can understand. It is however a tradeoff between abstraction and malleability. I'd rather see everything done in Smalltalk. Yet primitives not exposing its innards.
I think I just can't have the cake and have it, too.
yes, alas it is all about tradeoffs :-). But that's great. The more varieties the merrier.
For example in RSqueakVM (aka SPy) there is no immediate
Integer whatsoever. Yes, tagged ints are read during image startup but
they
aren't subsequently represented as immediates or tagged ints after that.
Well because it's implemented above RPython I guess it is using Python's bignum code directly. That's fine but its a bit of a cheat.
I was talking of SmallInts here. There is no bignum code involved. On the RPython side, SmallIntegers are just objects that have a field that is not accessible from Smalltalk but keeps a machine-word integer.
Hmmm, somewhere there's got to be a discrimination between SmallIntegers and other objects, right?
Just as input, in the Racket language and other Schemes,
the equivalent to our SmallInterger/LargeInteger is fixnum/bignum and for floats they have flonums and "extflonums" (80bit).
Best -Tobias
-- best, Eliot
Hi Eliot On 21.11.2014, at 19:56, Eliot Miranda <eliot.miranda@gmail.com> wrote:
Hi Tobias,
On Fri, Nov 21, 2014 at 10:52 AM, Tobias Pape <Das.Linux@gmx.de> wrote: Hi Eliot
On 21.11.2014, at 19:06, Eliot Miranda <eliot.miranda@gmail.com> wrote:
Hi Tobias,
On Fri, Nov 21, 2014 at 4:51 AM, Tobias Pape <Das.Linux@gmx.de> wrote:
Hi,
On 21.11.2014, at 13:44, Bert Freudenberg <bert@freudenbergs.de> wrote:
On 21.11.2014, at 13:29, J. Vuletich (mail lists) < juanlists@jvuletich.org> wrote:
Quoting Bert Freudenberg <bert@freudenbergs.de>:
I'd suggest BoxedDouble and ImmediateDouble as names for the concrete
subclasses (*). Names do mean something. (**)
You're right about the FloatArray confusion. However, note that the
IEEE standard calls it single and double. It's only C using "float" to mean "single precision".
I'd name the abstract superclass Float, for readability, and the
isFloat test etc. Also: "Float pi" reads a lot nicer than anything else. I don't see the need for having a deep LimitedPrecisionReal - Float - BoxedDouble/ImmediateDouble deep hierarchy now.
If we ever add single-precision floats, we should name them
BoxedSingle and ImmediateSingle. At that point we might want a Single superclass and a LimitedPrecisionReal supersuperclass, but we can cross that bridge when we get there.
- Bert -
(*) Since we're not going to see the class names often, we could even
spell it out as BoxedDoublePrecisionFloat and ImmediateDoublePrecisionFloat. Only half joking. It would make the relation to the abstract Float very clear.
(**) We could also try to make the names googleable. I was surprised
to not get a good hit for "boxed immediate". Only "boxed unboxed" finds it. Maybe there are two better words?
I very much agree with Bert. But I'd suggest SmallDouble instead of ImmediateDouble for consistency with SmallInteger.
Then it would have to be LargeDouble for consistency with LargeInteger, too. Which I don't find compelling.
Also, with the 64 bit format we get many more immediate objects. There already are immediate integers and characters, floats will be the third, there could be more, like immediate points. For those, the small/large distinction does not make sense.
Maybe Eliot's idea of keeping "Float" in the name was best, but instead of "small" use "immediate":
Float - BoxedFloat - ImmediateFloat
A Float is either a BoxedFloat or an ImmediateFloat, depending on the magnitude of its exponent.
I don't like the idea of putting a VM/Storage detail into the Class name. The running system itself does not care about whether Floats or Integers are boxed or immediate.
I disagree. I think at least Smalltalk-80 has a philosophy of lifting as much out of the VM into the system, and hiding it from clients via encapsulation. So unlike many other VMs the compiler is in the system, the system explicitly separates SmallInteger, LargePositiveInteger and LargeNegativeInteger and implements large integer arithmetic with Smalltalk code that uses SmallIntegers. Note that the primitives are an optional extra optimization that the VM does not need to implement. So for me it is in keeping with the current system to use BoxedFloat and SmallFloat or BoxedDouble and SmallDouble.
This lifting things up provides us with an extremely malleable system. Pushing things down into the VM does the opposite.
I can understand. It is however a tradeoff between abstraction and malleability. I'd rather see everything done in Smalltalk. Yet primitives not exposing its innards.
I think I just can't have the cake and have it, too.
yes, alas it is all about tradeoffs :-). But that's great. The more varieties the merrier.
For example in RSqueakVM (aka SPy) there is no immediate
Integer whatsoever. Yes, tagged ints are read during image startup but they aren't subsequently represented as immediates or tagged ints after that.
Well because it's implemented above RPython I guess it is using Python's bignum code directly. That's fine but its a bit of a cheat.
I was talking of SmallInts here. There is no bignum code involved. On the RPython side, SmallIntegers are just objects that have a field that is not accessible from Smalltalk but keeps a machine-word integer.
Hmmm, somewhere there's got to be a discrimination between SmallIntegers and other objects, right?
It is done. They are just objects but object identity is delegated to value identity [1]. All primitives know about this and they unwrap and rewrap the boxed machine int. It's just a straight-forward boxed implementation of integers. Where have I confused you?
Just as input, in the Racket language and other Schemes, the equivalent to our SmallInterger/LargeInteger is fixnum/bignum and for floats they have flonums and "extflonums" (80bit).
Best -Tobias
Best -Tobias [1]: https://bitbucket.org/pypy/lang-smalltalk/src/2a99a4827c84352bbd8344a327937c...
participants (2)
-
Eliot Miranda -
Tobias Pape