If you want the second keyword be "none" and not "do", you can use 2
templates/macros and a variable to pass state between them, like:
var whileSomeNone: bool
template whileSome*(condition: typed, body: untyped) =
whileSomeNone = condition
if whileSomeNone:
while true:
body
if not condition: break
template none*(body: untyped) =
if not whileSomeNone:
body
Run
No check is performed here that `none` follows `whileSome`, as downside.
May be used nested:
import whilesome
var a = 3 # set to >=7 for "none" branch
var b = 7
proc c: bool =
return a < b
whileSome(c()):
echo a
inc a
var i = 0 # set to >=3 for "none" branch
whileSome(i<3):
echo "i=", i
inc i
none:
echo "i >= 3 initially!"
none:
echo "No items to display!"
Run
