The only real question I have, is how do Ido this with the SFML shaders? I don't see a function for this in the documentation.
GLuint loc = glGetAttribLocation( program, "vPosition" );
glEnableVertexAttribArray( loc );
glVertexAttribPointer( loc, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );