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confused about the apply() operation

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I am confused about the operation of the apply(), when applied on and().

As far as I know, the apply() works in a way, that the elements of the second list argument are bouned to the formal argumets of a function provided as a first argument and then the function is called.
If I try
    apply('and list(list(1 2)) )
I obtain the following error :
*Error* eval: not a function - 1
However when trying and(list(1 2)) (what should be IMHO the same), the result is :
(1 2)

OK, so it looks like the apply() function calls eval on each element of the second argument. However, when trying
apply('print list(list(1 2) ) )
I obtain
(1 2)
nil

, what means that the eval is not called by apply(). Can someone explain this?

Thanks,
Miro








Originally posted in cdnusers.org by miro
Parents

  • Hi Miro,

    Well, it doesn't explicitly call it out as being a syntax form, but the fact that it says that it evaluates the arguments in turn suggests that.

    Note it doesn't strictly call eval() on each argument, because this is done at the byte code level, but you can visualize it as working that way.

    Most functions in SKILL (aka "lambda" functions) have their arguments evaluated for them before the function is called. Macros don't evaluate the arguments at all, but in fact run at compile time and transform the arguments into another form. syntax forms (and older "nlambda" functions) are called and passed the unevaluated arguments, and then choose within to selectively evaluate the arguments as needed. An obvious example is procedure() - clearly that would not make sense to evaluate the arguments before it is called!

    Regards,

    Andrew.

    Best Regards,

    Andrew.


    Originally posted in cdnusers.org by adbeckett
Reply

  • Hi Miro,

    Well, it doesn't explicitly call it out as being a syntax form, but the fact that it says that it evaluates the arguments in turn suggests that.

    Note it doesn't strictly call eval() on each argument, because this is done at the byte code level, but you can visualize it as working that way.

    Most functions in SKILL (aka "lambda" functions) have their arguments evaluated for them before the function is called. Macros don't evaluate the arguments at all, but in fact run at compile time and transform the arguments into another form. syntax forms (and older "nlambda" functions) are called and passed the unevaluated arguments, and then choose within to selectively evaluate the arguments as needed. An obvious example is procedure() - clearly that would not make sense to evaluate the arguments before it is called!

    Regards,

    Andrew.

    Best Regards,

    Andrew.


    Originally posted in cdnusers.org by adbeckett
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