Search icon CANCEL
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Haskell High Performance Programming
Haskell High Performance Programming

Haskell High Performance Programming: Write Haskell programs that are robust and fast enough to stand up to the needs of today

eBook
€22.99 €32.99
Paperback
€41.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
Table of content icon View table of contents Preview book icon Preview Book

Haskell High Performance Programming

Chapter 2. Choosing the Correct Data Structures

Perhaps the next most important topic in Haskell performance after lazy evaluation is data structures. I say the next most important because although data structures form a wider area than lazy evaluation, the unique performance aspects of lazy evaluation should deserve more attention. Still, structuring data efficiently is a must for performance, and in Haskell this often requires taking laziness into account, too.

Haskell gives the programmer lots of variety and clutches to structuring data, ranging from low-level primitives to ingenious, purely functional data structures. The traditional (re-)implementation costs associated with quick'n'dirty versus highly optimized solutions are really low in Haskell, and therefore there are even fewer reasons for complex premature optimizations in Haskell than in many other languages.

This chapter will help you to understand the performance semantics of Haskell values in general and...

Annotating strictness and unpacking datatype fields

Recall that in the previous chapter, we used seq to force strict evaluation. With the BangPatterns extension, we can force functions arguments. Strict arguments are evaluated WHNF just before entering the function body:

{-# LANGUAGE BangPatterns #-}

f !s (x:xs) = f (s + 1) xs
f !s      _ = s

Using bangs for annotating strictness in fact predates the BangPatterns extension (and the older compiler flag -fbang-patterns in GHC 6.x). With just plain Haskell98, we are allowed to use bangs to make datatype fields strict:

> data T = T !Int

A bang in front of a field ensures that whenever the outer constructor (T above) is in WHNF, the inner field is as well in WHNF. We can check this:

> T undefined `seq` ()
*** Exception: Prelude.undefined

There are no restrictions to which fields can be strict, be it recursive or polymorphic fields, although it rarely makes sense to make recursive fields strict. Consider the fully strict linked list:

data List...

Handling numerical data

Like all general-purpose programming languages, Haskell too has a few different number types. Unlike other languages, the number types in Haskell are organized into a hierarchy via type classes. This gives us two things:

  • Check sat compiletime we aren't doing anything insane with numbers
  • The ability to write polymorphic functions in the number type with enhanced type safety

An example of an insane thing would be dividing an integer by another integer, expecting an integer as a result. And because every integral type is an instance of the Integral class, we can easily write a factorial function that doesn't care what the underlying type is (as long as it represents an integer):

factorial :: Integral a => a -> a
factorial n = product [1..n]

The following table lists basic numeric types in Haskell:

Type

Size

Int

Signed integers, machine-dependent

Word

Unsigned integers, machine-dependent

Double

Double-precision floating point, machine-dependent

Float...

Handling binary and textual data

The smallest piece of data is a bit (0 or 1), which is isomorphic to Bool (True or False). When you need just one bit, a Bool should be your choice. If you need a few bits, then a tuple of Bools will fit the purpose when performance is not critical. A [Bool] is sometimes convenient, but should only be chosen for convenience in some situations.

For high-performance binary data, you could define your own data type with strict Bool fields. But this has an important caveat, namely that Bool is not a primitive but an algebraic data type:

data Bool = False | True

The consequence is that you cannot unpack a Bool similar to how you could an Int or Double. In Haskell, Bool values will always be represented by pointers. Fortunately for many bit-fiddling applications, you can define a data type like this:

data BitStruct = BitStore !Bool !Bool !Bool

This will get respectable performance. However, if you need a whole array of bits it quickly becomes inconvenient to define...

Handling sequential data

The standard list,[], is the most used data structure for sequential data. It has reasonable performance, but when processing multiple small values, say Chars, the overhead of a linked list might be too much. Often, the convenient nature of [] is convincing enough.

The wide range of list functions in Data.List are hand-optimized and many are subject to fusion. List fusion, as it is currently implemented using the foldr/build fusion transformation, is subtly different from stream fusion employed in ByteString and Text (concatMap is a bit problematic with traditional stream fusion). Still, the end result is pretty much the same; in a long pipeline of list functions, intermediate lists will usually not be constructed.

Say we want a pipeline that first increases every element by one, calculates intermediate sums of all elements up to current element, and finally sums all elements. From the previous chapter, we have learned to write optimally strict recursive functions...

Handling tabular data

If you need O(1) general indexing, a table-like data structure is virtually your only option. The Haskell report specifies the array package, which provides tables indexed by anything with an instance for a Ix typeclass.

Immutable arrays come in two flavors (we'll discuss mutable arrays later):

  • Data.Array.Array: Immutable arrays of boxed values
  • Data.Array.Unboxed.UArray: Immutable arrays of unboxed values

A common use case for Immutable arrays is memoization. For example, a table of Fibonacci numbers could be constructed as follows:

-- file: fib-array-mem.hs
import Data.Array

fib :: Int -> Array Int Integer
fib n = arr where
  arr = listArray (1,n) $ 1 : 1 : [ arr!(i-2) + arr!(i-1)| i <- [3..n] ]

We can also index by a tuple, which gives the array extra dimensions. The symmetric Pascal matrix will serve as an example:

pascal :: Int -> Array (Int, Int) Integer
pascal n = arr where
  arr = array ((1,1),(n,n)) $
    [ ((i,1),1) | i <- [1..n] ] ++
    [ ((1...

Annotating strictness and unpacking datatype fields


Recall that in the previous chapter, we used seq to force strict evaluation. With the BangPatterns extension, we can force functions arguments. Strict arguments are evaluated WHNF just before entering the function body:

{-# LANGUAGE BangPatterns #-}

f !s (x:xs) = f (s + 1) xs
f !s      _ = s

Using bangs for annotating strictness in fact predates the BangPatterns extension (and the older compiler flag -fbang-patterns in GHC 6.x). With just plain Haskell98, we are allowed to use bangs to make datatype fields strict:

> data T = T !Int

A bang in front of a field ensures that whenever the outer constructor (T above) is in WHNF, the inner field is as well in WHNF. We can check this:

> T undefined `seq` ()
*** Exception: Prelude.undefined

There are no restrictions to which fields can be strict, be it recursive or polymorphic fields, although it rarely makes sense to make recursive fields strict. Consider the fully strict linked list:

data List...

Handling numerical data


Like all general-purpose programming languages, Haskell too has a few different number types. Unlike other languages, the number types in Haskell are organized into a hierarchy via type classes. This gives us two things:

  • Check sat compiletime we aren't doing anything insane with numbers

  • The ability to write polymorphic functions in the number type with enhanced type safety

An example of an insane thing would be dividing an integer by another integer, expecting an integer as a result. And because every integral type is an instance of the Integral class, we can easily write a factorial function that doesn't care what the underlying type is (as long as it represents an integer):

factorial :: Integral a => a -> a
factorial n = product [1..n]

The following table lists basic numeric types in Haskell:

Type

Size

Int

Signed integers, machine-dependent

Word

Unsigned integers, machine-dependent

Double

Double-precision floating point, machine-dependent

Float

Single...

Handling binary and textual data


The smallest piece of data is a bit (0 or 1), which is isomorphic to Bool (True or False). When you need just one bit, a Bool should be your choice. If you need a few bits, then a tuple of Bools will fit the purpose when performance is not critical. A [Bool] is sometimes convenient, but should only be chosen for convenience in some situations.

For high-performance binary data, you could define your own data type with strict Bool fields. But this has an important caveat, namely that Bool is not a primitive but an algebraic data type:

data Bool = False | True

The consequence is that you cannot unpack a Bool similar to how you could an Int or Double. In Haskell, Bool values will always be represented by pointers. Fortunately for many bit-fiddling applications, you can define a data type like this:

data BitStruct = BitStore !Bool !Bool !Bool

This will get respectable performance. However, if you need a whole array of bits it quickly becomes inconvenient to define...

Handling sequential data


The standard list,[], is the most used data structure for sequential data. It has reasonable performance, but when processing multiple small values, say Chars, the overhead of a linked list might be too much. Often, the convenient nature of [] is convincing enough.

The wide range of list functions in Data.List are hand-optimized and many are subject to fusion. List fusion, as it is currently implemented using the foldr/build fusion transformation, is subtly different from stream fusion employed in ByteString and Text (concatMap is a bit problematic with traditional stream fusion). Still, the end result is pretty much the same; in a long pipeline of list functions, intermediate lists will usually not be constructed.

Say we want a pipeline that first increases every element by one, calculates intermediate sums of all elements up to current element, and finally sums all elements. From the previous chapter, we have learned to write optimally strict recursive functions...

Left arrow icon Right arrow icon
Download code icon Download Code

Key benefits

  • Explore the benefits of lazy evaluation, compiler features, and tools and libraries designed for high performance
  • Write fast programs at extremely high levels of abstraction
  • Work through practical examples that will help you address the challenges of writing efficient code

Description

Haskell, with its power to optimize the code and its high performance, is a natural candidate for high performance programming. It is especially well suited to stacking abstractions high with a relatively low performance cost. This book addresses the challenges of writing efficient code with lazy evaluation and techniques often used to optimize the performance of Haskell programs. We open with an in-depth look at the evaluation of Haskell expressions and discuss optimization and benchmarking. You will learn to use parallelism and we'll explore the concept of streaming. We’ll demonstrate the benefits of running multithreaded and concurrent applications. Next we’ll guide you through various profiling tools that will help you identify performance issues in your program. We’ll end our journey by looking at GPGPU, Cloud and Functional Reactive Programming in Haskell. At the very end there is a catalogue of robust library recommendations with code samples. By the end of the book, you will be able to boost the performance of any app and prepare it to stand up to real-world punishment.

Who is this book for?

To get the most out of this book, you need to have a working knowledge of reading and writing basic Haskell. No knowledge of performance, optimization, or concurrency is required.

What you will learn

  • Program idiomatic Haskell that s also surprisingly efficient
  • Improve performance of your code with data parallelism, inlining, and strictness annotations
  • Profile your programs to identify space leaks and missed opportunities for optimization
  • Find out how to choose the most efficient data and control structures
  • Optimize the Glasgow Haskell Compiler and runtime system for specific programs
  • See how to smoothly drop to lower abstractions wherever necessary
  • Execute programming for the GPU with Accelerate
  • Implement programming to easily scale to the cloud with Cloud Haskell
Estimated delivery fee Deliver to Luxembourg

Premium delivery 7 - 10 business days

€17.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Sep 26, 2016
Length: 408 pages
Edition : 1st
Language : English
ISBN-13 : 9781786464217
Vendor :
The Glasgow Haskell Team
Category :
Languages :
Tools :

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
Estimated delivery fee Deliver to Luxembourg

Premium delivery 7 - 10 business days

€17.95
(Includes tracking information)

Product Details

Publication date : Sep 26, 2016
Length: 408 pages
Edition : 1st
Language : English
ISBN-13 : 9781786464217
Vendor :
The Glasgow Haskell Team
Category :
Languages :
Tools :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 113.97
Haskell Cookbook
€41.99
Haskell Design Patterns
€29.99
Haskell High Performance Programming
€41.99
Total 113.97 Stars icon

Table of Contents

15 Chapters
1. Identifying Bottlenecks Chevron down icon Chevron up icon
2. Choosing the Correct Data Structures Chevron down icon Chevron up icon
3. Profile and Benchmark to Your Heart's Content Chevron down icon Chevron up icon
4. The Devil's in the Detail Chevron down icon Chevron up icon
5. Parallelize for Performance Chevron down icon Chevron up icon
6. I/O and Streaming Chevron down icon Chevron up icon
7. Concurrency and Performance Chevron down icon Chevron up icon
8. Tweaking the Compiler and Runtime System (GHC) Chevron down icon Chevron up icon
9. GHC Internals and Code Generation Chevron down icon Chevron up icon
10. Foreign Function Interface Chevron down icon Chevron up icon
11. Programming for the GPU with Accelerate Chevron down icon Chevron up icon
12. Scaling to the Cloud with Cloud Haskell Chevron down icon Chevron up icon
13. Functional Reactive Programming Chevron down icon Chevron up icon
14. Library Recommendations Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
(2 Ratings)
5 star 0%
4 star 50%
3 star 0%
2 star 50%
1 star 0%
Oswald Michael Nov 19, 2019
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
This book is ok to get an overview over performance in Haskell. On certain topics it does not delve very deep (which I would have wished for). But to get a bit of feel about what matters for performance in Haskell, it is really ok.Some Haskell source had a bad formatting inside (spaces got removed, so identifiers are not right), but with a little understanding it is clear what is meant.
Amazon Verified review Amazon
Kevin S. Van Horn Feb 26, 2020
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
The book is full of typos and inconsistencies that suggest the author never did a final review of the manuscript. New concepts (e.g. guarded recursion) are often ambiguously or incompletely defined, or defined only by example. Very sloppy writing.
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is the delivery time and cost of print book? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela
What is custom duty/charge? Chevron down icon Chevron up icon

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order? Chevron down icon Chevron up icon

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges? Chevron down icon Chevron up icon

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

  • If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
  • Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.
How can I cancel my order? Chevron down icon Chevron up icon

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela