doubt on fun

Corrado Santoro <>
Sun Jun 19 10:08:19 CEST 2005


MEENA SELVAM wrote:
> My doubt is what happens, when we put the fun as a
> parameter to a function. Since the fun is in the body,
> will the statements within the fun end block be
> executed just like any other expression?   
No, the fun/end block is executed when the function is evaluated.

I mean:

F = fun(X) -> X + 1 end.

This statement assigns to "F" the code of the fun. It is a simple 
assignment, not a "fun" execution.

When you write:

F(100)

you'll really execute the fun you declared above and get the result, 
"101" in this case.

When you pass a fun as a function parameter, a similar thing happens. 
The fun is assigned to an internal variable of the function and then it 
performs invocation, when needed.

> Similarly, what happens when fun... end is used as
> part of map as follows?
> 
> map(fun(X)->
>             {Y,Z}
>     end,
>     somelist)
> 
> In comparison with map(Func, List) applying Func to
> each element in the list, what does the above map with
> func .... end applies to the list?
It applies the fun to each element of the list as well. However, in your 
example, Z has to be bound to a value.

--Corrado

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