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[Axiom-developer] Re: [Aldor-l] exports and constants

From: Gabriel Dos Reis
Subject: [Axiom-developer] Re: [Aldor-l] exports and constants
Date: 24 Jul 2006 23:25:21 +0200

"Antoine Hersen" <address@hidden> writes:


| Also I do not know much about dependent type, but I think it is a run time
| feature only contrary to polymorphic type.

| So how much optimization can we hope to do ? For example can I do unboxing
| for my polynomial if I am not sure that they will be over machine integer at
| compile time ? Do we have to use dynamic language trick ?

for real word programs, this is still a reaserch topic.
So far, from experience, I can tell you that existing technologies are
good at exploiting invariant known at *compile-time*.  This is why
people still loves C or Haskell :-/


| The type system is quite unique and has some resemblance to modern typed
| language, for example aldor "Category", from far, look like Haskell "class
| type".

only on the surface.

| But from my limited knowledge, type as first class value and dependent type
| his quite unique.

not really.  See above and chase references in there.

| There is a paper about the aldor type system on I have not taken
| the time to read it completely but it could be a start even if it only
| represent a subset of Aldor.
| Chapter 18: Recomendation is very interesting.
| I will support the adition of algebraic datatype and I think any addition or
| modification that make Aldor closer to the popular modern functionall
| languages will be welcome.

This is a major addition.  One that I have been thinking of the last
two months.  I just don't know how to do it properly.  And I lack
a precise language description.
Algebraic datatype and "true" pattern matching help write very
readable codes.  Pattern matching is what makes Boot so enjoyable to

| Also some question that come in my mind :
| Do we need a "type system" for the type definition( think Haskell "kind") ?

Yes, we do.

| What about "pretend" is it really needed ? and the special place of Rep, rep
| and per ?

For any serious program yes.  Even, Haskell has unsafe stuff. 

| Is it possible to implement type inferrence ?

We need to have type inference for Aldor (or Axiom if we can wait that
long).  The explicit polymorphism à la System F is just unbearable by

| Are any modification needed to make it even more suited for programming
| computer algebra ?

We need way to "reflect" objects -- I'm awaiting Tim's work on pf2sex.
That should bring us a handle on way to better support generic
programming in Axiom.


| But a very large piece of un documented C code will not be very ususefull if
| nobody with a good knowledge of it is willing and able to spend a lot of
| time on cleaning( I think it does not compile under recent version of gcc),
| writing documentation and debugging( optimization above O1 does not seem to
| preserve semantic).

The same is true for any language, especially Lisp, Boot, or SPAD.

-- Gaby

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