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Learning Exercise
Sometimes when a function takes many arguments it can be difficult to remember the order they should be given in. To aid readability Gleam allows arguments to be labelled with a name.
To label an argument specify the label name before the argument name, separated by a space.
pub fn replace(
in string: String,
each target: String,
with replacement: String
) -> String {
// ...
}
When calling a function with labelled arguments the arguments can be given in any order. Each of these calls to replace are equivalent:
replace(in: "🍔🍔🍔", each: "🍔", with: "🍕")
replace(each: "🍔", in: "🍔🍔🍔", with: "🍕")
replace(with: "🍕", each: "🍔", in: "🍔🍔🍔")
Labels are always optional. Even if a function has labelled arguments they can still be called without labels.
replace("🍔🍔🍔", "🍔", "🍕")
You are the manager of a fancy restaurant that has a sizable wine cellar. A lot of your customers are demanding wine enthusiasts. Finding the right bottle of wine for a particular customer is not an easy task.
As a tech-savvy restaurant owner, you decided to speed up the wine selection process by writing an app that will let guests filter your wines by their preferences.
A bottle of wine is represented using a custom type, and wines are stored in a list.
[
Wine("Chardonnay", 2015, "Italy", White),
Wine("Pinot grigio", 2017, "Germany", White),
Wine("Pinot noir", 2016, "France", Red),
Wine("Dornfelder", 2018, "Germany", Rose)
]
Implement the wines_of_color function. It should take a list of wines and return all wines of a given color.
wines_of_color(
[
Wine("Chardonnay", 2015, "Italy", White),
Wine("Pinot grigio", 2017, "Germany", White),
Wine("Pinot noir", 2016, "France", Red),
Wine("Dornfelder", 2018, "Germany", Rose)
],
color: White
)
// -> [
// Wine("Chardonnay", 2015, "Italy", White),
// Wine("Pinot grigio", 2017, "Germany", White),
// ]
Implement the wines_from_country function. It should take a list of wines and return all wines from a given country.
wines_from_country(
[
Wine("Chardonnay", 2015, "Italy", White),
Wine("Pinot grigio", 2017, "Germany", White),
Wine("Pinot noir", 2016, "France", Red),
Wine("Dornfelder", 2018, "Germany", Rose)
],
country: "Germany"
)
// -> [
// Wine("Dornfelder", 2018, "Germany", Rose)
// ]
Implement the filter function. It should take a list of wines, a color and a country and return all wines of the given color bottled in the given country.
filter(
[
Wine("Chardonnay", 2015, "Italy", White),
Wine("Pinot grigio", 2017, "Germany", White),
Wine("Pinot noir", 2016, "France", Red),
Wine("Dornfelder", 2018, "Germany", Rose)
],
color: White
country: "Italy"
)
// -> [
// Wine("Chardonnay", 2015, "Italy", White),
// ]
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