function pointers in structs

[glycerine]

gi> type S struct {
  f func(string, ...interface{}) }
error! __errHandlerForEval sees err =   [string "--..."]:2326: attempt to call field 'substr' (a nil value)
[string "--..."]:2326: attempt to call field 'substr' (a nil value)
stack traceback:
    [string "--..."]:3262: in function 'substr'
    [string "--..."]:2326: in function '__funcType'
    [string "..."]:6: in function 'chunk'
    [string "--..."]:3290: in function <[string "--..."]:3290>
    [C]: in function 'xpcall'
    [string "--..."]:3290: in function '__gijitMainEval'
    [string "--..."]:3322: in function <[string "--..."]:3322>

elapsed: '810.463µs'
gi>