Editing ZuriHac2015 (section)

== Talks ==

The links to the slides of the talks can be found on the [https://github.com/meiersi/HaskellerZ#2015-meetups '''HaskellerZ github page'''].

=== Edward Kmett ===
Title: Discrimination is Wrong: Improving Productivity

Abstract:
This talk is a case study in library design in Haskell.

Fritz Henglein has shown through a number of excellent papers how to use "discrimination" to do lots of things in O(n): Sorting many more data types than you'd expect, table joins, etc.

In the process of optimizing this approach and wrapping it up in a form that can be easily consumed, we'll take a lot of detours through the different ways you can think about code when optimizing Haskell.

* We'll need some category theory, from a deeper understanding of monoids to Day convolution.
* We'll need to consider final and initial encodings.
* We'll need to drift down to low level system concerns from building a custom foreign prim to nesting unsafePerformIO within unsafePerformIO.
* We'll need properties of laziness from productivity to IVars.

Along the way we'll find and fix a small problem with the initial discrimination paper, which opens the door to streaming results, rather than having to wait until all the input is ready.

=== Duncan Coutts ===
Title: Better faster binary serialization

Abstract:

This talk is a case study in low level optimization in Haskell.

We have existing libraries for binary serialization but the mainstream
ones use bad formats, and could always be faster. We will look at new
work to improve on the existing libraries, to use a new better format,
and to dramatically improve performance.

We will go into the details of a number of standard and new techniques
for getting a good combination of performance with features and
flexibility.

* High+low level approach to eliminating unnecessary allocations in deserialization
* Surprising use of deep embeddings and interpreters
* Moving work from compiled code to an interpreter
* Rewrite rules to improve interpreted code
* Deep embedding of composition to give statically allocated descriptions of branching programs
* Types to safely use unsafe low level data structures
* Looking at STG code to see allocations and other problems
* Fast path / slow path tricks
* Explicit control stacks
* ABIs / calling conventions for unknown functions

There'll be plenty of code, types and benchmarks.

=== Jannis Limperg ===
Title: Monads by example

Abstract: The Monad type class is used extensively in both the Haskell standard
library and numerous third-party libraries for all sorts of domains.
Yet, it is also one of the most infamous roadblocks for Haskell
beginners, which this talk aims to address.

In order to build an intuition for what a Monad 'is' and especially for
how it's useful in everyday programming, we will take a look at several
important instances of the Monad class from the standard library (and
the de-facto standard transformers package): Maybe, Either, [], State
and IO. The examples will focus for the most part on how these very
different types are all instances of the abstract concept of a Monad,
and how using this abstraction and the associated syntactic sugar (do
notation) can lead to cleaner, more readable code. Afterwards, we will
take a look at how the Monad class is defined by a set of simple laws
that every Monad instance must obey. Time permitting, we may also touch
upon slightly more advanced topics such as Monad transformers and how
Monads are related to Functors and Applicative Functors.

Prerequisites: [http://learnyouahaskell.com/chapters LYAH] up to and including chapter 8 (or of course
anything else that covers the same topics). In particular, a basic
understanding of algebraic data types and type classes is essential.

=== Oliver Charles ===
Title: An Introduction to Web Programming

Abstract: For many people, Haskell is not their first programming language - a lot of us learnt to program in other languages like Python or Java, and would like to be able to use Haskell to solve practical problems. However, what seem to be simple web applications in other languages can be daunting to even begin using Haskell. In this talk, we'll look at how to build a small web application to allow ZuriHac participants to share what they have been working on. We'll use the Spock web framework along with postgresql-simple to build a basic CRUD application, and see how we can start prototyping a simple web application within minutes.

=== Gergely Risko ===
Title: Template Haskell

Abstract: Template Haskell is the meta programming extension for GHC.  In this
talk we will investigate and livecode some basic concepts of code
generation and code introspection provided by this facility.  We will
also take a look on an example: the hflags command line parsing
library.

=== Mathieu Boespflug ===
Title: Distributed Programming

Abstract: Shifting from building compilers and desktop applications to online
services and mobile apps means that Haskell programming is
increasingly about building systems, not standalone data-in data-out
contraptions. Systems that are distributed across anything from a
handful to millions of machines. We'll look at what Haskell has to
offer for building robust and scalable distributed systems, starting
from the paradigms popularized in other languages to more idiomatic,
safe and composable models.

=== Johan Tibell ===
Title: Performance

Abstract: Production quality code not only needs to compute the correct result,
but needs to do so within some given resource constraints (i.e. time
and memory). We'll look at the most common optimizations you can use
to make your Haskell code perform better and some rules of thumb you
can use in your daily Haskell programming to avoid some performance
problems "by design".