> > f x = x + x
> > Is the "x" use to create a pattern in the definition and when f is
> > called it's replaced by a value?
>
>Those equation-like definitions are syntactic sugar for lambda
>abstractions. f could as well be defined as f = \x -> x + x.
Please elaborate
First, the
f x =
part says that f is a function which takes a single parameter,
called x. The other side of the = sign gives the function body: in
this case, x + x. This is exactly the same thing that is expressed
by the lambda expression
\x -> x + x
This expression defines a function that takes a single parameter
called x, and returns the value of x + x. The only difference is
that with the lambda expression, this function is not given a
name. But you can easily give the function a name (just as you can
give any Haskell expression a name) by writing
f = \x -> x + x
In general, writing
g x y z = blah blah
is just a shorthand for
g = \x -> \y -> \z -> blah blah.
That is, it simultaneously creates a function expression, and
assigns it a name.
Does that help?
Yes and thanks for the reply.
When a function is declared in C the argument variable has an address
somewhere in the memory:
int f ( int x ) {
return x * x;
}
any value passed to f() is assigned to x. x is the identifier for a
real slot in the memory (the stack most likely) made available for f().
Is this also what happens in Haskell?
Thanks, Paul
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