# Multiple Square Bracketed Function definition

I am familiar with the typical way of defining a function--such as

f[x_,y_]:=x+y


but I have not found a discussion of definitions such as

torus[a_,b_,c_][p_,q_][u_,v_]:= {(a+b Cos[u])Cos[v],(a+b Cos[u])Sin[v},c Sin[u]}


I am not asking about this specific example but the f[][][]:= structure as opposed to the usual f[]:= simpler one. Can someone point me to a discussion?

• perhaps you'll find this useful; (look for SubValues) – user42582 Apr 15 '18 at 20:26
• – Bob Hanlon Apr 15 '18 at 20:52
• – kglr Apr 15 '18 at 20:54