Difference between revisions of "Closure"

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m (fixed typo)
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f x = (\y -> x + y)
 
f x = (\y -> x + y)
 
</haskell>
 
</haskell>
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<hask>f</hask> returns a closure, because the variable <hask>x</hask>, which is bound outside of the [[lambda abstraction]] is used inside its definition.
 
<hask>f</hask> returns a closure, because the variable <hask>x</hask>, which is bound outside of the [[lambda abstraction]] is used inside its definition.
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An interesting side note: the context in which <hask>x</hask> was bound shouldn't even exist anymore, and wouldn't, had the lambda abstraction not closed around x.
 
An interesting side note: the context in which <hask>x</hask> was bound shouldn't even exist anymore, and wouldn't, had the lambda abstraction not closed around x.

Latest revision as of 13:53, 1 January 2017

A closure, the opposite of a combinator, is a function that makes use of free variables in its definition. It 'closes' around some portion of its environment. for example

f x = (\y -> x + y)

f returns a closure, because the variable x, which is bound outside of the lambda abstraction is used inside its definition.


An interesting side note: the context in which x was bound shouldn't even exist anymore, and wouldn't, had the lambda abstraction not closed around x.