On Thu, 27 Dec 2007 14:37:51 +0200, Yitzchak Gale <[EMAIL PROTECTED]> wrote:
I wrote:
Like any type, only certain operations make
sense on functions...
Yes, but one can store the result of an operation to disk except in
the
particular case the result happen to be a function.
No, you can only store the result of an operation to
disk in the particular case that the result type represents
a list of bytes. Otherwise, you have to serialize it first...
But it is not clear at all how you could define a general
serialization method for functions.
Isn't that confusing levels of abstractions ?
Of course functions are bytes, 'cause they are already stored as bytes
in
RAM.
That is just the point. A function in Haskell is an abstraction,
not bytes in RAM.
The compiler might IMPLEMENT the same function in several places,
with different bytes in each place. Or it might decide to combine it
into other functions, and not store any bytes in RAM at all for this
function.
See ?
The function itself represents a way of doing a calculation. It is not an
object that can do the calculation.
Then trees of functions are ...
I'm not sure that in Haskell one can say that storing a value
of some type to disk is an operation defined on that type.
It is. For example:
hPutStr :: Handle -> String -> IO ()
And this is a property of the type String ?
The function hPutStr appears in the definition of the type String ?
Ah, you are thinking of "operation on a type" in the OOP sense.
Sorry, I wasn't clear. When I said "only certain operations make
sense" on each type, I just meant that there are only certain
things you can do with the type. In Haskell, the things you can
do with a type are the functions you can define that mention that
type in their signature.
How can one define in the language STORAGE of "things" ?
Storage of numbers for example ?
You said that the TYPE of a function forbids me somehow to store it in a
file.
Now I understand that not the type forbids me, but the lack of a function
with apropriate types.
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