> Melenchon […] started as a Trostkist

So did more than half of the socialist party elit (elephant du PS), even freaking Cambadelis, are you suggesting he’s far left to ?

> against the capitalist system

Well yes, almost by definition of being on the left I would argue.

> So if you think Le Pen is extreme on one side then Melenchon has to be equally extreme on the other side.

No, this is a false equivalence. I mean the far-left as a political position does exist in France, but it is not represented by Melenchon who is still largely a socialist, although the actual socialist party has significantly shifted rightward in the 10's so there is a perception issue there.