Quoting Ralf Hemmecke [EMAIL PROTECTED]:
All the exports that appear are basically the
exports of the Union (OK, Union still has a few more.)
---BEGIN aaa.as
#include aldor
#include aldorio
define ET: Category == with; -- ExpressionType
Expr: ET with {
MkInt: Integer - %;
It
Bill Page [EMAIL PROTECTED] writes:
| Quoting Ralf Hemmecke [EMAIL PROTECTED]:
|
|
| All the exports that appear are basically the
| exports of the Union (OK, Union still has a few more.)
|
| ---BEGIN aaa.as
| #include aldor
| #include aldorio
|
| define ET: Category == with; --
Bill Page [EMAIL PROTECTED] writes:
[...]
| in Haskell, by a kind of convenient abuse of notation
| (or polymorphism if you wish) 'MkInt' also denotes a
| function
|
|MkInt: Int - MkInt Int
Bill --
you're highly confused.
On 05/09/2007 10:02 AM, Bill Page wrote:
No, I think there is a serious misunderstanding here. What
Gaby is talking about are algebraic data types. See for
example:
http://en.wikipedia.org/wiki/Algebraic_data_type
In Gaby's example Haskell code:
data Expr = MkInt Int
| MkAdd
Quoting Ralf Hemmecke [EMAIL PROTECTED]:
On 05/09/2007 10:02 AM, Bill Page wrote:
...
MkInt is *not* a function which when given an Integer
returns something of type Expr. It is type *constructor*,
that is, when given 'Int' MkInt returns a subtype of Expr.
Before you criticize... I
Dear Bill,
I only have a comment on the following.
I agree that it's a source of confusion. But I must admit that
I would have written
MkInt: Int - Expr
instead. Otherwise there would be a type mismatch in
eval (MkInt i) = i
since MkInt(Int) is not equal to Expr. Don't you agree?
On Wed, 9 May 2007, Ralf Hemmecke wrote:
| And I cannot say whether MkInt is a type constructor in Haskell, since I don't
| know the language very well.
MkInt is NOT a type constructor in Haskell; Bill was very confused.
MkInt is a *data* constructor, and your understanding is correct.
-- Gaby
On Wed, 9 May 2007, Bill Page wrote:
[...]
| ... in Haskell, by a kind of convenient abuse of notation
| (or polymorphism if you wish) 'MkInt' also denotes a
| function
|
| MkInt: Int - MkInt Int
|
| that creates an object of type 'MkInt Int' from an object
| in 'Int'. I think
Quoting Ralf Hemmecke [EMAIL PROTECTED]:
Dear Bill,
I only have a comment on the following.
I agree that it's a source of confusion. But I must admit that
I would have written
MkInt: Int - Expr
instead. Otherwise there would be a type mismatch in
eval (MkInt i) = i
since
Quoting Gabriel Dos Reis [EMAIL PROTECTED]:
On Wed, 9 May 2007, Bill Page wrote:
[...]
| ... in Haskell, by a kind of convenient abuse of notation
| (or polymorphism if you wish) 'MkInt' also denotes a
| function
|
| MkInt: Int - MkInt Int
|
| that creates an object of type
Well, I did not interepret it as a slur against Haskell. However, it did
appear to me to be fundamentally incorrect to miss the core ideas of
algebraic data typea and how they lead to GADT:
data Expr where
MkInt:: Integer - Expr
MkAdd:: Expr - Expr - Expr
MkMul:: Expr -
Bill Page [EMAIL PROTECTED] writes:
| Quoting Gabriel Dos Reis [EMAIL PROTECTED]:
|
| On Wed, 9 May 2007, Bill Page wrote:
|
| [...]
|
| | ... in Haskell, by a kind of convenient abuse of notation
| | (or polymorphism if you wish) 'MkInt' also denotes a
| | function
| |
| |
On Wed, 9 May 2007, Ralf Hemmecke wrote:
| Well, I did not interepret it as a slur against Haskell. However, it did
| appear to me to be fundamentally incorrect to miss the core ideas of
| algebraic data typea and how they lead to GADT:
| data Expr where
|MkInt:: Integer - Expr
On Tue, 8 May 2007, Bill Page wrote:
| I have more to say later.
|
| We're listening. :-)
One of the issues I have with many of the various alternatives is
that they make definition of new functions operating on Expr
also impossible (by a third person) without intimate knowledge
of the
On 05/08/2007 05:21 PM, Gabriel Dos Reis wrote:
One of the issues I have with many of the various alternatives is
that they make definition of new functions operating on Expr
also impossible (by a third person) without intimate knowledge
of the representation of Expr, or modifying the Expr
Quoting Ralf Hemmecke:
...
I know the definitions in aaa.as look quite lengthy, but it probably
shows how one could generically generate appropriate Aldor code
from a more concise Syntax.
Since Aldor is already intended to be pretty concise, I don't think
it is a good idea in general to try
... I know the definitions in aaa.as look quite lengthy, but it probably
shows how one could generically generate appropriate Aldor code
from a more concise Syntax.
Since Aldor is already intended to be pretty concise, I don't think
it is a good idea in general to try to invent a new language
Ooops, I overlooked something.
---BEGIN bbb.as
#include aldor
#include aldorio
#library EXPR aaa.ao
import from EXPR;
extend Expr: OutputType == add {
import from 'MkInt', 'MkAdd', 'MkMul';
import from Integer;
(tw: TextWriter) (x: %): TextWriter == {
x case MkInt = tw
On Tue, 8 May 2007, Ralf Hemmecke wrote:
| But I thought that the Haskell
|
| data Expr = MkInt Int
| | MkAdd Expr Expr
| | MkMul Expr Expr
|
| is more like
|
| Union(Cross(Tag, Int),
| Cross(Tag, Expr, Expr),
| Cross(Tag, Exrp, Expr)).
yes, conceptually, that
Quoting Ralf Hemmecke [EMAIL PROTECTED]:
...
Bill Page wrote:
Ralf, these are just general comments about your approach and
aren't intended to be particularly critical.
Although I felt that it was the most critical reaction on one of my
mails that I have ever experienced from you, I know
By the way. Today I have learned how to include an integer
into the left or right part of Union(left: Integer, right:
Integer). There appears only an example in the AUG, but not a formal
description.
Please tell. I missing the example. I think this is quite important.
That should have been
Dear Gaby,
Gabriel Dos Reis [EMAIL PROTECTED] writes:
For concretness, here is a very classic example of inductive type
along with a function working on expression of such type, written in
both Haskell and New Boot. How would you best write that in Spad?
I'm very sorry, but I do not
On May 7, 2007 2:28 AM Martin Rubey writes:
Gabriel Dos Reis writes:
For concretness, here is a very classic example of inductive
type along with a function working on expression of such type,
written in both Haskell and New Boot. How would you best write
that in Spad?
I'm very
Here you go. But I doubt somehow that Gaby had this in mind, since this is
quite usual stuff in Axiom (grep Rep.*Union)
Martin
)abbrev domain EX Expr
Expr(): with
eval: % - Integer
coerce: Integer - %
coerce: % - OutputForm
_+: (%,%) - %
_*: (%,%) - %
== add
MkInt ==
Martin,
On May 7, 2007 4:14 AM you wrote:
Here you go. But I doubt somehow that Gaby had this in mind,
since this is quite usual stuff in Axiom (grep Rep.*Union)
...
Fantastic! Thankyou. See it again here:
http://wiki.axiom-developer.org/SandBoxInductiveType
I believe that is exactly
Martin Rubey [EMAIL PROTECTED] writes:
| Dear Gaby,
|
| Gabriel Dos Reis [EMAIL PROTECTED] writes:
|
|For concretness, here is a very classic example of inductive type
| along with a function working on expression of such type, written in
| both Haskell and New Boot. How would you best
http://wiki.axiom-developer.org/SandBoxInductiveType
I've added an Aldor version.
Ralf
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On May 7, 2007 10:41 AM Gaby wrote:
Martin Rubey writes:
| Here you go. But I doubt somehow that Gaby had this in
| mind, since this is quite usual stuff in Axiom
(grep Rep.*Union)
Thanks, Martin.
I did not say I did not know how to write it. I said I don't
have a good way :-).
Hi,
While writing a tutotial on programming with Spad, I realize that
I don't have a good way to present inductive types in Spad. I know
what they would like in my ideal Spad, but we don't have that ideal
Spad yet. So, I'm asking here how you would write inductive types
in today Spad.
For
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