France lost a lot by joining the euro: What to make of this?

A recent German study (Centre for European political studies in Freiburg) shows that France has lost significant income by joining the euro. The simple argument is that the inability to devalue to correct the competitiveness disadvantage has been highly detrimental. We believe caution is called for with such an argument. In contemporary economies, an exchange rate devaluation boosts the exposed sector (industry, exportable services), but reduces real income and domestic demand; The size of France's gross external debt, mainly in euros, in any case makes an exit from the euro impossible; It is completely true that French industry should have adjusted when the country joined the euro (modernisation, move up the value chain, etc.).