FRENCH LEANINGS TOWARD AVANT-GARDE

For the moment the French appetite for ''Louis'' furniture, from Quatorze through Philippe, has more or less had it in favor of high-tech and surrealistic furniture that once in a while actually turns out to be functional. Yet the most prized treasures are chairs you can't sit on, beds you can't sleep in, pianos that don't play.

President Francois Mitterrand appears to be as ardent an admirer of modern abstraction as the late Georges Pompidou, who has the honor of having the Beaubourg Museum (often mistaken for an oil refinery) named after him. Like his predecessor, Mitterand has refurbished several of the private apartments at the Elysees Palace with some extremely odd-looking artifacts.

Tradition definitely seems to be taking a back seat, and many a rather pretentious madame currently tends to sound like a cracked Victrola record with that boring refrain of countersnobbism, ''Oh, I'm so tired of valuable antiques, having been surrounded with them all my life.'' The connotation is that the speaker was born and raised in the Chateau de Versailles while everyone else grew up with art objects from Woolworth's and wouldn't be sharp enough anyhow to tell the difference between Louis Quinze and Frank Lloyd Wright.

There are salons devoted to furniture, sculpture, and endless things one doesn't know how to describe - all as futuristic as the 21st century or vaguely retrospective, suggesting the Bauhaus influence from the 1930s. The annual Salon des Artistes Decorateurs takes over the Grand Palais every winter, with almost 700 avant-garde creators from the Common Market countries exhibiting for a period of three weeks. One can admire such objects as the chair made out of a T-shirt or the one-legged piano that wouldn't work even if the late Arthur Rubinstein were seated at the keyboard. Although things are seldom what they seem, they still may perform some utilitarian function. The piano might eventually turn out to be a cabinet concealing a TV set or a computer.

While the most eccentric examples are generally destined strictly for show, certain ''museum pieces'' have wended their way into expositions at the Musee des Arts Decoratifs. There are also numerous private collectors, according to a spokesman at the Salon des Artistes Decorateurs. These connoisseurs are willing and able to pay prices often running into the equivalent of several thousand dollars for some piece that is one of a kind.

Following so much ''Americana'' in Europe (it all started with jeans and hamburgers), part of this art impetus originally came from the United States. A couple of years ago a touring exhibit called ''Real Art'' sponsored by Uncle Sam was installed for six weeks at the Grand Palais. Crowds, lined up for hours before the main entrance, eventually wandered around inside in a state of ecstasy before such works as a life-size worm-ridden telegraph pole propped over a heap of rocks and the enormous canvas painted a solid, unrelieved black, including the frame.

Personally, although I am an avid gallery-goer, I cannot conceive of any friends who might be impressed by a rotting telegraph pole beamed across the center of our living room, nor do I feel that those black ''paintings'' belong anywhere except in a funeral establishment. If all that's ''art,'' please take me back to the Louvre.

The current exposition of desks and office furniture at the Musee des Arts Decoratifs is slightly more realistic, even fairly functional if one embraces the trend for desks without drawers. The bureau is now as streamlined as the Concorde. Apparently the abolition of drawers indicates that the high-powered executive, or ''PDG'' (president-director general), has no need to concern himself with such banalities as files, documents, or correspondence - the indication being that it's all filed up there in his brilliant mind.

If drawers are becoming obsolete, so are closets and cupboards in many decorating schemes, which tend to appear as stark and uncluttered as a Japanese bedroom. ''Continuity is all-important,'' says one advocate who goes to the ultimate extreme of running the wall-to-wall carpeting right up the walls and across the ceiling.

Where do you hang your wardrobe? No matter! By the time you've paid for all the fanciful decor, there's not a sou left over to buy any clothes.