One year after casting their ballots for the most radical political change in their post-World War II history, the French do not much like what they voted for but nonetheless would reelect Socialist Francois Mitterrand as their president.

Even in a land known for cultivating paradoxes, that seemingly contradictory verdict is confirmed by one recent opinion poll after another.

As problems accumulate here as in every other major industrialized nation beset by recession, the Socialists have discovered that last year they were not voted in so much as their conservative opponents were voted out after an unbroken 23 years in power.

The Socialists seem honestly surprised that, after an initial half-year honeymoon, they are now confronted by that morose and somewhat sour public mood that long has been a national political trait.

After all, they argue in self-defense, politicians in most countries are berated for not living up to their campaign promises. Here, with a few notable exceptions, the Socialists have systematically enacted into law a cascade of promises only to discover that reforms are not that popular and voters are more worried about the struggling economy.

On the other hand, the French seem to have accepted the Socialists without major upset. It is hard to remember that in the first months following the Socialist victory, many people feared that the society would fall into chaos. Instead Mitterrand, a telling critic of the Fifth Republic's constitution during his long spell in the opposition, has surprised the nation by the obvious pleasure and skill with which he wields the powers that former president Charles de Gaulle had hand-tailored for himself.

By parliamentary vote--or by decree during a three-month period--the Socialists have set in motion measures destined to change the face of France.

Through sweeping and controversial nationalization schemes, almost all private-sector banking and giant industrial groups have become government-owned, increasing the public sector's share of industry from 16 to more than 30 percent.

The Socialists have given salaried workers a fifth week of paid vacation, greatly increased the minimum wage and family and old-age benefits, instituted retirement at 60 and reduced the work week from 40 to 39 hours with promises of 35 hours to come.

Moonlighting immigrant workers have been issued proper papers. The poorest workers have been issued government-subsidized "vacation checks" to let them enjoy paid holidays at resorts and also have had their government savings accounts protected against inflation.

The Socialists have abolished the death sentence and the Star Chamber-like state security courts and military tribunals. A tough law assuming the guilt of anyone detained during a riot has been repealed, and other repressive laws are also scheduled to be junked this spring.

Both the polls and conservative victories in local elections in March show that the French are less concerned with reforms than with the country's economic troubles, which they fear will increase as time goes by.

Inflation is no worse than under defeated president Valery Giscard d'Estaing. But at between 13 and 14 percent it has not improved much at a time when France's principal trading partners, especially West Germany, have sharply reduced their inflation rates.

Nor are the other major economic indicators encouraging.

Despite determined efforts to fight unemployment, the government's proclaimed number-one objective, just under 2 million French workers--more than the number a year ago--are jobless.

Devalued slightly last fall, the franc only staved off another devaluation this spring at the cost of massive outlays of foreign exchange reserves.

Gaping deficits afflict the ponderous social security system--larger than the state budget--and the balance of trade and balance of payments. Capital investment declined 7 percent last year, partly because of business distrust of government motives.

In the first flush of electoral victory, the Socialists tried classic Keynesian pump-priming in hopes that the lackluster economy they inherited would respond.

It didn't, and analysts have begun scaling down government hopes for achieving 3 percent growth this year. The Socialists have blamed high U.S. interest rates; most economists blame the failure of any other major trading partner to reflate and this gives a boost to France.

Many important Socialists remark in private that the few times in this century that the left has come to power here, it has been swept in because of an economic mess bequeathed by its predecessors.

Another major Socialist concern is the government's seemingly uncontrollable penchant for contradictory statements and actions, which cannot be explained away only by ministerial inexperience due to a quarter century in the political wilderness.

Under the Socialist banner, moderates and conservatives, central planners and free enterprise advocates, law and order defenders and liberal reformers all slug it out in public.

Pierre Mauroy, a compromise prime minister acceptable to all the rival socialist clans, horrified the tougher party leaders and delighted the conservatives by defending his acceptance of what critics denounce as near anarchy and incoherence.

The government is expected to be reshuffled--insiders say the announcement could come in early summer--to weed out the weaker ministers.

Within the ruling coalition, the Socialists have proved masters at controlling the Communists, their junior government partners.

Much anguish was expressed at home and abroad--especially in Washington--when Mitterrand included Communists in the government for the first time since 1947. The four Communist ministers have proved loyal and efficient--and their party has continued to lose votes in each successive election.

Mitterrand has stayed aloof from the everyday workings of government--at least publicly--apparently afraid of falling victim to the overexposure that helped cost Giscard reelection.

Despite the restiveness of the Socialist parliamentarians--many of them ideologically minded schoolteachers--Mitterrand has his way with the party.

It was his decision, for example, not to honor campaign promises to reduce drastically France's ambitious nuclear program or halve military service to six months.

Thanks to hard-line policies against the Soviets and in favor of increased defense spending, he has achieved better relations with the United States than any French leader since the 1950s.

He has also put aside, perhaps only momentarily, his own deep misgivings about hard-line American policy in Central America, which he considers bound to increase, rather than reduce, communist influence there.

His most dramatic gesture in other foreign policy matters has been giving up his predecessors' pro-Arab tilt in favor of an even-handed approach toward Israel while openly advocating a Palestinian state, which is anathema to the Israeli government.

Undeterred by the conservatives' increasingly shrill attacks, Mitterrand knows his greatest strength lies in the powers he enjoys under the constitution.

"I will carry out my mandate until the expiration date" fixed by the constitution, which is 1988, he said recently.