I have recently been experimenting writing code that replaces large
chunks of the Prelude, compiling with -fno-implicit-prelude. I notice
that I can happily redefine numeric literals simply by creating functions
called 'fromInteger' and 'fromRational': GHC will use whatever is in
scope for tho
, and not worry about types at all.
>
> I accept that this might be a slightly bizarre request. There are a
> number of things I don't like about the way the Prelude.Monad class and
> 'do' notation are set up, and it would be nice to be able to experiment
> with alte
Ashley writes
| > I was hoping to do something similar for 'do' notation by redefining
| > (>>), (>>=) etc., but unfortunately GHC is quite insistent
| that 'do' notation quite specifically refers to GHC.Base.Monad
Dylan replies
| I'm surprised that ghc uses the fromInteger and fromRational
Ping!
At 2002-05-14 07:17, Simon Peyton-Jones wrote:
>Ashley writes
>
>| > I was hoping to do something similar for 'do' notation by redefining
>| > (>>), (>>=) etc., but unfortunately GHC is quite insistent
>| that 'do' notation quite specifically refers to GHC.Base.Monad
>
>Dylan replies
>
>
I'm fond of the idea proposed by Marcin 'Qrczak' Kowalczyk:
| May I propose an alternative way of specifying an alternative
Prelude?
| Instead of having a command line switch, let's say that 3 always
means
| Prelude.fromInteger 3 - for any *module Prelude* which is in scope!
That's a perfe
At 2002-07-15 01:05, Simon Peyton-Jones wrote:
>I quite like the fact that you would then have to say
>
> import MyPrelude as Prelude
>
>thereby stressing that you are importing the Prelude stuff.
Doesn't this assume your Prelude stuff is all in one module? Or can you
import several modu
> | anymore. What I would like is that the defualting rules refer
> | to the classes in my version of the Prelude,
> | not the Standard Prelude.
>
> You can always get that (with the -fno-implicit-prelude thing) by adding
> default [Int, Double]
>
> or whatever to your source module, jus
Hi All,
Thanks to everyone for their comments.
I can see that this is quite a difficult design problem, and it is
unlikely that one solution will please everyone, which makes me think
that the current solution will probably stand.
Simon Peyton-Jones writes:
> Bernie writes:
> | anymore. What
Hi again,
Malcolm writes:
> We came across the same problem in the Hat tracer (which is also a
> source-to-source transformation, and can also be used for debugging).
>
> The problem is that the transformation introduces new classes, so
> Prelude.Ord -> HatPrelude.Ord
> Prelude.Eq -> Ha
> > The defaulting mechanism *only* applies to types constrained by
> > the original builtin Prelude.Num, not to the transformed class
> > HatPrelude.Num.
>
> I did wonder how Hat tackled this.
> Out of curiosity what is the solution that Hat uses?
Hat doesn't have a solution. When the lack of
Malcolm Wallace wrote:
> > For what reasons do you require the original prelude?
>
> Exactly the same reasons. We want to do as little desugaring as
> necessary in the transformation, so inevitably we need at least a
> small part of the Prelude in scope.
This is a bit misleading. We do desugar
Malcolm writes:
> Bernie writes:
> > I did wonder how Hat tackled this.
> > Out of curiosity what is the solution that Hat uses?
>
> Hat doesn't have a solution. When the lack of correct defaulting
> causes Hat to generate type-incorrect code, the underlying compiler
> will complain vociferousl
|Ambiguities in the class Num are most common, so Haskell
| provides another
|way to resolve them---with a default declaration:
|default (t1 , ... , tn)
|where n>=0, and each ti must be a monotype for which Num ti holds.
| ^^
On Tue, Jul 16, 2002 at 04:02:44PM +1000, Bernard James POPE wrote:
> I would like to use do-notation in the transformed program, but have it
> refer to Prelude.Monad and not MyPrelude.Monad which is also in scope.
Why do you have a MyPrelude.Monad (different from Prelude.Monad) if
you don't want
Dylan writes:
> On Tue, Jul 16, 2002 at 04:02:44PM +1000, Bernard James POPE wrote:
> > I would like to use do-notation in the transformed program, but have it
> > refer to Prelude.Monad and not MyPrelude.Monad which is also in scope.
>
> Why do you have a MyPrelude.Monad (different from Prelude.
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