repos / handle-examples.hs.git

commit

7d69f11

parent

1703c53

author

Evgenii Akentev

date

2023-04-01 00:27:33 +0400 +04

[row-handle]: add examples of row types

 1@@ -25,3 +25,29 @@ getWeatherData = getMethod @"getWeatherData"
 2 
 3 getWindData :: Handle -> Location -> Day -> IO WindProvider.WindSpeed
 4 getWindData = getMethod @"getWindData"
 5+
 6+-- Some examples of what else is possible with row types.
 7+
 8+-- We can remove an item from the record
 9+type WindAndTemperatureMethods = Methods .- "getWeatherData"
10+
11+test1 :: Rec WindAndTemperatureMethods -> Rec (WindProvider.Methods .+ TemperatureProvider.Methods)
12+test1 = id
13+
14+-- It's possible to override methods
15+type MethodsWithUpdatedWeatherData = ("getWeatherData" .== (Location -> Day -> IO Int)) .// Methods
16+
17+test2 :: Rec MethodsWithUpdatedWeatherData -> Rec (("getWeatherData" .== (Location -> Day -> IO Int)) .+ WindProvider.Methods .+ TemperatureProvider.Methods)
18+test2 = id
19+
20+-- And to remove them by taking a row difference
21+type MethodsWithoutWeatherData = Methods .\\ ("getWeatherData" .== (Location -> Day -> IO WeatherData))
22+
23+test3 :: Rec MethodsWithoutWeatherData -> Rec WindAndTemperatureMethods
24+test3 = id
25+
26+-- The minimum join of the two rows.
27+type JoinedMethods = Methods .\/ Methods
28+
29+test4 :: Rec JoinedMethods -> Rec Methods
30+test4 = id