A excerpt of my talk about Erlang and Powerset's use of it at Microsoft on 12/4/08. Please feel free to distribute, but do not modify.

1. Erlang Essentials
Core Language Features of Interest
Excerpt From 12/4/08 Microsoft Presentation
Slides by Dave Fayram
dfayram@microsoft.com
© 2008 Powerset

2. Erlang Basics
• A Functional Language
• Based around pattern matching, a total
lack of shared state, and a flexible
message passing system.
• Lightweight Processes are just tail-
recursive functions executing in parallel.
© 2008 Powerset

3. Erlang Example
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4. Pattern Matching
• Erlang has no assignment.
• Every “=” statement forms a relationship.
• Type descriptions are also valid for pattern
matching.
© 2008 Powerset

5. Pattern Matching
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6. Lightweight Processes
• Any function (named or anonymous) can
become a process.
• A process is simply a function executing in
parallel.
• Process semantics mirror function
semantics.
© 2008 Powerset

7. Lightweight Processes
• Extremely Efficient!
• Modern systems can accommodate
literally millions of Erlang processes.
• Erlang LWP can be run in parallel on
multiple CPUs.
• Programs heavily reliant on processes
tend to get free performance boosts.
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8. Lightweight Processes
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9. Lightweight Processes
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10. Asynchronous Messages
• The “!” operator sends messages.
• Asynchronous, no guarantee of delivery.
• The “receive” statement matches messages.
• One call to receive, one message
removed from the process message
queue.
• Uses Pattern Matching to select messages
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11. [target] ! [message]
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12. Asynchronous Messages
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13. Asynchronous Messages
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14. Asynchronous Messages
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15. Asynchronous Messages
• Erlang does not distinguish between “local”
processes and “remote” processes.
• This is the core of Erlang’s distributed
programming.
• Semantics are identical (already, no strong
guarantees of message delivery).
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16. Asynchronous Messages
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17. Asynchronous Messages
© 2008 Powerset