Trying to calculate a sum within a module - why is the iterator not creating integers?

Question

Suppose I have the code:

#!/usr/local/bin/MathematicaScript -script
SetOptions[$Output, FormatType -> OutputForm];

foo[bar_?IntegerQ, baz_?IntegerQ] = bar;

M[g_?IntegerQ] = Module[
    {sum},
    sum = Sum[foo[i, g], {i, 1, 4} ];
    N[sum]
];

Print[M[1]]

Why does this output:

foo[1., 1] + foo[2., 1] + foo[3., 1] + foo[4., 1]

When simply changing the g to a 1 as following correctly interprets the iterator as an integer?

#!/usr/local/bin/MathematicaScript -script
SetOptions[$Output, FormatType -> OutputForm];

foo[bar_?IntegerQ, baz_?IntegerQ] = bar;

M[g_?IntegerQ] = Module[
    {sum},
    sum = Sum[foo[i, 1], {i, 1, 4} ];
    N[sum]
];

Print[M[1]]

This outputs (as expected):

10

Answer 1

You get your desired result by invoking the SetDelayed option for your functions. To output an Integer, remove the N[] function.

#!/usr/local/bin/MathematicaScript -script
SetOptions[$Output, FormatType -> OutputForm];

foo[bar_?IntegerQ, baz_?IntegerQ] := bar;

M[g_?IntegerQ] := Sum[foo[i, g], {i, 1, 4}];

Print[M[1]]

(*10*)