Am Mittwoch, den 16.11.2011, 10:46 +0100 schrieb Bas van Dijk:
Is ⊥ the right symbol to express the non-strict evaluation of the
language? Is it true that non-strict evaluation requires that ⊥
inhabits every type?
In typical strict languages, ⊥ also inhabits every type. The difference
is that
No.
Am Mittwoch, den 23.11.2011, 13:11 -0600 schrieb heathmatlock:
Question: Do you want a mascot?
Answers:
Yes
No
--
This is an attempt to figure out if this idea is going anywhere.
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://ghc.haskell.org/trac/ghc/ticket/10009 might be the same
regression (fixed in HEAD)
Regards,
Adam
On Tue, Jun 2, 2015 at 12:28 PM, Wolfgang Jeltsch
g9ks1...@acme.softbase.org wrote:
Hi,
the following (contrived) code is accepted by GHC 7.8.3
Hi,
the following (contrived) code is accepted by GHC 7.8.3, but not 7.10.1:
{-# LANGUAGE TypeFamilies #-}
type family F a :: *
type family G b :: *
x :: G (F a) ~ a = F a
x = undefined
GHC 7.10.1 reports:
Could not deduce (F a0 ~ F a)
from the context (G (F a) ~ a)
bound by
Am Samstag, den 22.07.2017, 23:03 -0400 schrieb Ben Gamari:
> In addition, there are a number of new features,
>
> * A new, more type-safe type reflection mechanism
>
> * The long-awaited Backpack module system
>
> * Deriving strategies to disambiguate between GHC's various instance
>
h the parse function returns one. It just ignores
> the ParseFailed case. I was going to try fixing it and send a pull
> request when I ran into the Cabal 2.* problem.
>
> On Wed, Jul 26, 2017 at 7:15 AM, Ben Gamari <b...@smart-cactus.org>
> wrote:
> >
> > Wolfgang
gt;
>
> In short, fundeps and type family dependencies only add extra
> unification constraints, which may help to resolve ambiguous
> types. They don’t provide evidence. That's not to say that they
> couldn't. But you'd need to extend System FC, GHC's core language, to
> do so.
Hi!
The base package contains the module Data.Type.Equality, which contains
the type (:~:) for homogeneous equality. I was a bit surprised that
there is no type for heterogeneous equality there. Is there such a type
somewhere else in the standard library?
I tried to define a type for
Hi!
Injective type families as supported by GHC 8.0.1 do not behave like I
would expect them to behave from my intuitive understanding.
Let us consider the following example:
> {-# LANGUAGE RankNTypes, TypeFamilyDependencies #-}
>
> class C a where
>
> type T a = b | b -> a
>
> instance
Am Sonntag, den 18.06.2017, 12:02 -0700 schrieb wren romano:
> > > {-# LANGUAGE Rank2Types, TypeFamilies #-}
> > >
> > > import GHC.Exts (Constraint)
> > >
> > > type family F a b :: Constraint
> > >
> > > data T b c = T
> > >
> > > f :: (forall b . F a b => T b c) -> a
> > > f _ = undefined
>
Hi!
In my previous e-mail, I showed some code that uses the Constraint kind.
I forgot to enable the ConstraintKinds extension though, but GHC 8.0.1
did not complain. Is this a bug?
All the best,
Wolfgang
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Hi!
Today I encountered for the first time the notion of an “untouchable”
type variable. I have no clue what this is supposed to mean. A minimal
example that exposes my problem is the following:
> {-# LANGUAGE Rank2Types, TypeFamilies #-}
>
> import GHC.Exts (Constraint)
>
> type family F a b
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