Yield in Mathematica

Question

Can you do something like Python's yield statement in Mathematica, in order to create generators? See e.g. here for the concept.

Update Here's an example of what I mean, to iterate over all Permutations, using only O(n) space: (Algorithm as in Sedgewick's Algorithms book):

gen[f_, n_] := Module[{id = -1, val = Table[Null, {n}], visit},
  visit[k_] := Module[{t},
    id++; If[k != 0, val[[k]] = id];
    If[id == n, f[val]];
    Do[If[val[[t]] == Null, visit[t]], {t, 1, n}];
    id--; val[[k]] = Null;];
  visit[0];
  ]

Then call it it like:

gen[Print,3], printing all 6 permutations of length 3.

Answer 1

You probably mean the question to be more general but the example of iterating over permutations as given on the page you link to happens to be built in to Mathematica:

Scan[Print, Permutations[{1, 2, 3}]]

The Print there can be replaced with any function.