Say I have a list that contains weather:
1> Weather = [{toronto, rain}, {montreal, storms}, {london, fog},
{paris, sun}, {boston, fog}, {vancouver, snow}].To get foggy places, I could do this:
2> FoggyPlaces = [X || {X, fog} <- Weather].
[london,boston]Now I want to retrieve places that are both foggy and snowy. I tried this, but it retrieves only snowy places,
3> FoggyAndSnowyPlaces = [X || {X, fog} <- Weather, {X,snow} <- Weather].
[vancouver,vancouver]where I was expecting [london,boston,vancouver].
How can I include multiple filters?
Anonymous User
22-May-2015FoggyAndSnowyPlaces = [X || {X, Y} <- Weather, (Y == fog) or (Y == snow)].