Definitions | t T, reduce(f;k;as), Y, filter(P;l), mapfilter(f;P;L), map(f;as), concat(ll), x:A. B(x), as @ bs, True, b, P  Q, , ff, tt, i <z j,  b, i z j, nth_tl(n;as), hd(l), P & Q, i j < k, ||as||, {i..j }, l[i], if b then t else f fi , isl(x), outl(x), x(s), A, False, P   Q, Unit, ,  |