A Small Contribution to Phobos

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I saw a thread a few days ago about somebody wanting a few 
UFCS-based convenience functions, so I thought that I'd take the 
opportunity to make a small contribution to Phobos. Currently I 
have four small functions: each, exhaust, perform, and tap, and 
would like some feedback.

each is designed to perform operations with side-effects on each 
range element. To actually change the elements of the range, each 
element must be accepted by reference.

Range each(alias fun, Range)(Range r)
if (isInputRange!(Unqual!Range))
{
    alias unaryFun!fun _fun;
    foreach (ref e; r)
    {
        fun(e);
    }

    return r;
}

//Prints [-1, 0, 1]
[1, 2, 3].each!((ref i) => i -= 2).writeln;


exhaust iterates a range until it is exhausted. It also has the 
nice feature that if range.front is callable, exhaust will call 
it upon each iteration.

Range exhaust(Range)(Range r)
if (isInputRange!(Unqual!Range))
{

    while (!r.empty)
    {
        r.front();
        r.popFront();
    }

    return r;
}

//Writes "www.dlang.org". x is an empty MapResult range.
auto x = "www.dlang.org"
         .map!((c) { c.write; return false; })
         .exhaust;

//Prints []
[1, 2, 3].exhaust.writeln;


perform is pretty badly named, but I couldn't come up with a 
better one. It can be inserted in a UFCS chain and perform some 
operation with side-effects. It doesn't alter its argument, just 
returns it for the next function in the chain.

T perform(alias dg, T)(ref T val)
{
    dg();

    return val;
}

//Prints "Mapped: 2 4"
[1, 2, 3, 4, 5]
.filter!(n => n < 3)
.map!(n => n * n)
.perform!({write("Mapped: ");})
.each!(n => write(n, " "));


Lastly is tap, which takes a value and performs some mutating 
operation on it. It then returns the value.

T tap(alias dg, T)(auto ref T val)
{
    dg(val);

    return val;
}

class Foo
{
    int x;
    int y;
}

auto f = (new Foo).tap!((f)
{
    f.x = 2;
    f.y = 3;
});

//Prints 2 3
writeln(f.x, " ", f.y);

struct Foo2
{
    int x;
    int y;
}

//Need to use ref for value types
auto f2 = Foo2().tap!((ref f)
{
    f.x = 3;
    f.y = 2;
});

//Prints 3 2
writeln(f2.x, " ", f2.y);


Do you think these small functions have a place in Phobos? I 
think each and exhaust would be best put into std.range, but I'm 
not quite sure where perform and tap should go. Also, there's 
that horrible name for perform, for which I would like to come up 
with a better name.