Title here
Summary here
Switch in PureScript
Here’s how to translate the provided code example to PureScript:
Switch Statements
Switch statements express conditionals across many branches.
module Main where
import Prelude
import Effect (Effect)
import Effect.Console (log)
import Data.Time (now, weekday, DayOfWeek(..))
main :: Effect Unit
main = do
-- Here’s a basic `switch`.
let i = 2
log $ "Write " <> show i <> " as "
case i of
1 -> log "one"
2 -> log "two"
3 -> log "three"
_ -> pure unit
-- You can use commas to separate multiple expressions in the same `case` statement.
-- We use the optional `default` case in this example as well.
currentTime <- now
let currentDay = weekday currentTime
case currentDay of
Saturday -> log "It's the weekend"
Sunday -> log "It's the weekend"
_ -> log "It's a weekday"
-- `switch` without an expression is an alternate way to express if/else logic.
-- Here we also show how the `case` expressions can be non-constants.
let currentHour = currentTime.hour
case currentHour of
hour | hour < 12 -> log "It's before noon"
_ -> log "It's after noon"
-- A type `switch` compares types instead of values.
-- You can use this to discover the type of a value.
let whatAmI i =
case i of
_ :: Boolean -> log "I'm a bool"
_ :: Int -> log "I'm an int"
_ -> log $ "Don't know type " <> show i
whatAmI (true :: Boolean)
whatAmI (1 :: Int)
whatAmI ("hey" :: String)To run the program, ensure you have PureScript and Spago installed, and follow these steps:
- Place the code in
Main.purs. - In your project directory, install the necessary dependencies:
spago install - Build and run the program using:
spago run
You should see the output as:
Write 2 as
two
It's a weekday
It's after noon
I'm a bool
I'm an int
Don't know type "hey"Let’s learn more about PureScript!