data World = World (Marble, Ball, Flag)
data Marble = Marble(Number, Number, Number, Number)
data Ball = Ball (Number, Number, Number, Number)
data Flag = Flag (Number, Number)
data FlagF = FlagF (Number, Number)

main = simulationOf(initial, step, picture)

initial(rs) = World (initialMarble,initialBall,initialFlag)
initialMarble = Marble(-8,8,3,-1)
initialBall = Ball (11,4,3,5)
initialFlag = Flag (7,-7)
initialFlagF = FlagF (6,-7)

step(world,dt)= gravity(world,dt)

gravity(x,y,xv,yv)
|x > 4 = (x,y)
|y < 7 = (x,y)
|xv > 6 = (xv, yv)
|yv < 5 = (xv, yv)
|otherwise = (x,y,xv,yv)

picture = (World(m,b,f,ff)&marble(m)&ball(b)&flag(f)&flagF(ff)

marble(m) = colored(translated(solidCircle(1),-8,8),red) <------ Parse Error
ball(b) = colored(translated(solidCircle(1), 11,4),cyan)
flag(f) = colored(translated(solidRectangle(1,5),gray),7,-7)
flagF(ff) = colored(translated(solidRectangle(1,4),green),6,-7)

link wont work srry

The problem is on the previous line.  That's normal for parse errors, because most of the time, the computer doesn't realize there's anything wrong until it gets to the next line.

In the definition of picture, I think you wanted something like this:

picture(World(m, b, f, ff)) = marble(m) & ball(b) & flag(f) & flagF(ff)