Life is too short for imperative programming

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Life is too short for imperative programming

• John Hughes

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Software Crisis, 1968today

• Software project outcomes

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In Large Companies
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Technology adoption life cycle
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Technology adoption life cycle
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Technology adoption life cycle
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The Erlang Story

• 1986Erlang emerges at Ericsson
• Functional language
• Extra support for concurrency fault tolerance
• Early 1990ssmall products
• 1996
• Open Telecoms Platform (higher-order functions
  for robust telecom systems)
• AXD 301 project starts

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The AXD 301

• ATM switch (telephone backbone)
• Born out of a failed project!
• 1,5 MLOC Erlang
• Seven nines reliability
• 4-10x better productivity, quality

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Erlang Story II

• 1998Erlang banned for new projects
• 1998Open source Erlang
• 1998Bluetail
• Jane Walerud VD
• Mail robustifier, Web prioritizer

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SSL Accelerator

• Alteon WebSystems' SSL Accelerator offers
  phenomenal performance, management and
  scalability.
• Network Computing

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Kreditor
Order 100-
invoice
Order details
Kreditor
100-
97-
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• Founded May 2006
• Selling QuickCheck!
• Extra feature simplifies failing tests

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Session Border Gateway A Firewall for IP
telephony
Monitors signalling traffic opens and closes
pinholes
2x1G Ethernet Linux blade processor
Media Gateway Controller
Opens media pin-holes for calls in progress
Media Proxy
2x10G Ethernet Hardware for packet forwarding
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Session Border Gateway A Firewall for IP
telephony
Media Gateway Controller
InterWork Description defines a subset
ITU standard protocol H.248 (Megaco)
Media Proxy
150KLOC Erlang
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Session Border Gateway A Firewall for IP
telephony
QuickCheck
Media Proxy
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Megaco Commands
Context
Context
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Megaco Commands
Context
Context
Context
Termination
Add
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Megaco Commands
Context
Context
Add
Context
Termination
Termination
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Megaco Commands
Context
Context
Context
Termination
Termination
Modify
Stream
Stream
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Megaco Commands
Context
Context
Subtract
Context
Termination
Termination
Stream
Stream
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Megaco Commands
Context
Context
Context
Termination
Subtract
Stream
Stream
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Megaco Commands
Context
Context
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Command Sequences

• Normal sequence

We wanted to test other sequences that, according
to the IWD, should work.
Add
Modify
Add
Subtract
Modify
Subtract
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Add/Modify Error

• Modify assumes there are already two terminations
  in the context
• Same bug found in virtually every run!
• New bug precondition needed for Modify

Add
Modify
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Add/Subtract Error

• There one day, gone the next
• This bug had just been found and fixed by the
  development team

Add
Subtract
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Add/Add/Modify Error

• If the terminations have different numbers of
  streams
• Same underlying problem Modify assumes each
  stream has two ends

Add
Add
Modify
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Add/Add/Sub/Add Error

• Extracted from a test case 160 commands long
• Caused by corrupt data-structures after the first
  Subtract

Add
Add
Add
Subtract
Subtract
Add
Subtract
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• Derivatives trading in New York

10 Microsoft shares
Option to buy ? for 100 anytime In 2007
Option to sell ? for 10 in Nov 2006
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How do they do it?
C plugins
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Simon Peyton-Jones Financial Contracts in Haskell

• The option to acquire 10 Microsoft shares, for
  100, anytime between t1 and t2 years from now

anytime Contract -gt Contract -- Acquire the
underlying contract at -- any time before it
expires (but -- you must acquire it)
anytime Choose when
golden_handcuff anytime shares shares zero
or (scaleK -100 (one Dollar) and
scaleK 10 (one MSShare))
MS shares are a currency
or Choose whether
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New Approach
Haskell contract models
C plugins
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• Functional programming on Wall Street
• Proprietary trading
• 60 people
• OCaml primary development language

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The Cat Among the Pigeons
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The Cat Among the Pigeons

• Two cores, each hyperthreaded