Generator pattern - background, basics and use cases around the pattern. I talk through some of the fundamentals of functional programming, continuation passing style and closures before landing up in iterators and generators. While there exits a good number of scenarios where the generators are useful, I pick a handful of them which I think are handy and unique.

1. Show and tell:
Generator patterns and new use
cases
Gireesh Punathil, IBM India
gpunathi@in.ibm.com | @gireeshpunam | https://github.com/gireeshpunathil

2. Agenda
• Functional Programming
• Continuation passing style
• Closures and Closure Contexts
• Iterator patterns
• Generator patterns
• Generator pattern use cases
• Summary
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3. Functional Programming
• A programming language paradigm in which computation is the
evaluation of function(s)
• Functions as first class variables
• Higher order functions
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4. Continuation Passing Style
• A functional programming style in which the caller delegates both the
current as well as the continuation control flow to the callee.
Continuation retention style Continuation passing style
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5. Closure
• Binding of a function and its operating environment that is defined in
the lexical scope of an enclosing function.
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6. Closure context
• The operating environment that is defined in the lexical scope of an
enclosing function.
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7. Iterator Pattern
• An object oriented programming pattern which defines an
Enumerator interface that traverses Components in a Container
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Java Javascript

8. Generator Pattern
• An programming pattern which defines an Controller interface for
incrementally traversing a data structure / executing a code sequence
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9. Generator Pattern Use cases: #1
• Simple iterator over heterogeneous collections
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10. Generator Pattern Use cases: #2
• Implement stream sources in a clean manner
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11. Generator Pattern Use cases: #3
• Traverse deeply nested data structures, yield intermediary values
while retaining the traversal context
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12. Further reading
Functional Programming
https://en.wikipedia.org/wiki/Functional_programming
Continuation passing style
https://en.wikipedia.org/wiki/Continuation-passing_style
Closures and Closure Contexts
https://www.ibm.com/developerworks/library/wa-use-javascript-
closures-efficiently
Iterators and Generators
https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Iterators
_and_Generators
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