function code instances in Lua _lua

In Lua, a function is a "first class value" that has a specific lexical domain.

First Class value: Representation in Lua, functions have the same rights as other traditional types of values (numbers and strings), functions can be stored in a variable (whether global or local) or in a table, can be passed as arguments to other functions, and can be returned as values for other functions.

Lexical fields: Refers to a function that can be nested within another function. Internal functions can access variables in external functions.
See Example code:

Copy Code code as follows:

Todo
function foo (A, B, c)
Print (A, B, c);
End

Local c = foo;
C (2, 3, 4);

End

The output results are: 2, 3, 4

Example:

Copy Code code as follows:

Todo
function derivative (f, Delta)
Delta = Delta or 0.01
Print ("Delta:", Delta);
return function (x)
Return (f (x + Delta)-f (x))/Delta
End
End
Local c = derivative (Math.sin)
Print (Math.Cos), C (10))
End

In the example above,

Copy Code code as follows:

c = function (x) return (Math.sin (x + 0.1)-math.sin (x))/0.01

Because:

Copy Code code as follows:

Local c = derivative (Math.sin)

Will:

Copy Code code as follows:

f = Math.sin