Non-local variable: Difference between revisions

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Revision as of 22:31, 3 November 2011

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In [[programming language theory]], a '''non-local variable''' is a variable that is not defined in the local scope. While the term can refer to global variables, it is primarily used in the context of [[nested function|nested]] and [[anonymous function]]s where can some variablevariables can be in neither in the [[local scope|local]] nor in the [[global scope]].

== Example ==

In the example that follows there is a nested function <code>inner</code> defined in the scope of another function <code>outer</code>. The variable <code>x</code) is local to <code>outer</code>, but non-local to <code>inner</code> (nor is it global):

<source lang=python>

def outer():

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</source>

In this next example the variable c is non-local in the anonymous function <code>\x -> x + c</code>:

<source lang=haskell>

outer = let c = 1 in map (\x -> x + c) [1, 2, 3, 4, 5]