# News aggregator

### Haskell Weekly News

*Top Picks:*
- Team GHC announces the first release candidate of version 8.0
<http://haskell.1045720.n5.nabble.com/ANNOUNCE-Glasgow-Haskell-Compiler-8-0-1-release-candidate-1-td5827003.html>.
New features include:
- Strict and StrictData extensions
- TypeFamilyDependencies extension for injective type families
<https://ghc.haskell.org/trac/ghc/wiki/InjectiveTypeFamilies>
- TypeInType extension for more dependent typing hackery
- explicit type application in plain Haskell, not Core
- Applicative do-notation
- a spanking new pattern-match checker
- modularization of the ghci interpreter: it can now run as an
independent process
Note that the announcement includes a list of bugs linked to the new
features.
- The engineers at an Australian real estate listings website explain
how they "used Category Theory to solve a problem in Java."
<http://techblog.realestate.com.au/how-we-used-category-theory-to-solve-a-problem-in-java/>
They face the

Categories: Incoming News

### Call for Participation: BOB 2016 (February 19, Berlin)

Quick reminder: the early registration deadline for BOB 2016 is this Sunday!
We have some interesting Haskell talks and tutorials at BOB 2016!
================================================================
BOB 2016
Conference
"What happens if we simply use what's best?"
February 19, 2016
Berlin
http://bobkonf.de/2016/
Program:
http://bobkonf.de/2016/program.html
Registration:
http://bobkonf.de/2016/registration.html
================================================================
BOB is the conference for developers, architects and decision-makers
to explore technologies beyond the mainstream in software development,
and to find the best tools available to software developers today.
Our goal is for all participants of BOB to return home with new
insights that

Categories: Incoming News

### Proposal: Add Semigroup and Monoid instances for (:~:)

These are not likely to be *useful*, but they fall easily into the
general bucket of "exactly one sensible instance exists".
instance Semigroup (a :~: b) where
r <> _ = r
instance a ~ b => Monoid (a :~: b) where
mempty = Refl
mappend r _ = r

Categories: Offsite Discussion

### GHC.Generics and instances of Functor, Applicative, etc?

I'm using GHC.Generics and have noticed that the data types defined there
don't have instances of the standard classes (at least not defined in that
module), such as Functor, Applicative, Foldable and Traversable. It'd be
very useful to be able to rely on such instances, so that one can define
instances of custom types via instances of the generic types. (Hopefully,
the compiler can remove most or all conversion overhead) Is there any
reason not to add these generic instances?

Categories: Offsite Discussion

### Proposal: Add Peano numbers to base

I have seen these redefined many times now. Examples:
https://hackage.haskell.org/package/numericpeano-0.2.0.0/docs/Numeric-Peano.html#t:Nat
https://hackage.haskell.org/package/numeric-prelude-0.4.2/docs/Number-Peano.html#t:T
https://hackage.haskell.org/package/type-fun-0.0.1/docs/TypeFun-Data-Peano.html#t:N
https://hackage.haskell.org/package/number-0.1.1.0/docs/Data-Number-Peano.html#t:Nat
https://hackage.haskell.org/package/Peano-0.0.4/docs/Data-Peano.html#t:Peano
I often see them used as DataKinds. Too, operations on them can be
lazy, which is sometimes useful.
I filed a ticket: https://ghc.haskell.org/trac/ghc/ticket/11402
Discussion period: 2 weeks

Categories: Offsite Discussion

### Eq1, Ord1, Show1: move from eq1, compare1, showsPrec1 to liftEq, liftCompare, liftShowsPrec

In transformers-0.5:Data.Functor.Classes class methods like eq1 are
replaced by liftEq.
With transformers-0.4 I could define:
data T a = complicated definition ...
deriving (Eq, Ord, Show)
instance Eq1 T where eq1 = (==)
instance Ord1 T where compare1 = compare
instance Show1 T where showsPrec1 = showsPrec
In transformers-0.5 it seems that I have to implement Eq1, Ord1, Show1
instances manually. Is there some assistance to define eq1 and compare1
for an ADT? What are the use cases where eq1 was not powerful enough and
liftEq is needed?

Categories: Offsite Discussion

### New gtk2hs 0.12.4 release

Thanks to John Lato and Duncan Coutts for the latest bugfix release! The latest packages should be buildable on GHC 7.6, and the cairo package should behave a bit nicer in ghci on Windows. Thanks to all!

~d

Categories: Incoming News