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needs to be built in order to locate the non-local variables. If the nested function is returned as a result from its outer function (or stored in a variable) the non-local variables will no longer be available on the stack. They need to be heap allocated instead, and their lifetime extends beyond
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the lifetime of the outer function that declared and allocated them. This generally requires garbage-collection.
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only points to the local variable of the nested function itself and there can be an arbitrary number of
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Non-local variables are the primary reason it is difficult to support nested, anonymous,
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If the nested function is passed as an argument to a higher-order function a
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In computer programming, a variable which is not defined in the local scope
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Aho, Lam, Sethi, and Ullman. "7.3 Access to
Nonlocal Data on the Stack".
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In
Javascript, the locality of a variable is determined by the closest
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In the Python 3 example that follows there is a nested function
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on the stack in between. This is generally solved using
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statement for this variable. In the following example,
371:If the nested function or functions are (mutually)
282:In the Haskell example that follows the variable
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27:is a variable that is not defined in the local
449:Compilers: Principles, Techniques, & Tools
383:the non-local variable was allocated, as the
43:where some variables can be in neither the
79:defined in the scope of another function
35:, it is primarily used in the context of
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286:is non-local in the anonymous function
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182:doesn't. Therefore, x is non-local to
352:Nested function § Implementation
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425:Programming in Lua (first edition)
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31:. While the term can refer to
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379:to know exactly where on the
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471:Variable (computer science)
466:Programming language theory
368:in a programming language.
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21:programming language theory
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375:, it becomes hard for the
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366:first-class functions
346:Implementation issues
95:(nor is it global):
58:they are called the
278:Anonymous functions
91:, but non-local to
41:anonymous functions
389:activation records
25:non-local variable
452:. Second edition.
431:27.3.3 – Upvalues
397:display registers
178:statement, while
174:as it contains a
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49:global scope
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460:Categories
441:References
381:call stack
350:See also:
373:recursive
377:compiler
218:function
191:function
127:nonlocal
66:Examples
60:upvalues
47:nor the
404:closure
242:console
354:, and
263:return
154:return
37:nested
411:Notes
328:->
295:outer
266:inner
221:inner
194:outer
184:inner
180:inner
176:var x
172:outer
157:inner
142:print
121:inner
103:outer
93:inner
89:outer
81:outer
77:inner
45:local
29:scope
39:and
23:, a
395:or
316:map
301:let
248:log
203:var
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124:():
118:def
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100:def
56:Lua
54:In
19:In
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313:in
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337:c
334:+
331:x
325:x
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319:(
310:1
307:=
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298:=
284:c
272:}
269:;
260:}
254:x
251:(
245:.
239:;
236:1
230:x
227:{
215:;
212:1
209:=
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200:{
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148:x
145:(
139:1
133:x
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109:x
85:x
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