add function support to defaultProps

[rkmax]

I'm using 3.2.24

I found this pretty useful for things like this

const Sample = t.struct({
  type: t.String,
  createdAt: t.Date
}, {
  defaultProps: {
    type: 'SAMPLE',
    createdAt: function() {
      return new Date();
    }
  }
});

[gcanti]

@rkmax what about a getter?

const Sample = t.struct({
  type: t.String,
  createdAt: t.Date
}, {
  defaultProps: {
    type: 'SAMPLE',
    get createdAt() {
      return new Date();
    }
  }
});

[rkmax]

@gcanti thank you that works, I feel dumb :man_facepalming: overthinking it