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|
import expect
doc """
Result represents the result of something that may succeed or fail.
`Ok` means it was successful, `Error` means it failed.
"""
pub enum Result(error, value) =
| Ok(value)
| Error(error)
;
pub fn is_ok(result) {
case result {
| Error(_) -> False
| Ok(_) -> True
}
}
test is_ok {
is_ok(Ok(1)) |> expect:true
is_ok(Error(1)) |> expect:false
}
pub fn is_error(result) {
case result {
| Ok(_) -> False
| Error(_) -> True
}
}
test is_error {
is_error(Ok(1)) |> expect:false
is_error(Error(1)) |> expect:true
}
pub fn map(result, fun) {
case result {
| Ok(x) -> fun(x)
| Error(_) -> result
}
}
test map {
Ok(1)
|> map(_, fn(x) { x + 1 })
|> expect:equal(_, Ok(2))
Error(1)
|> map(_, fn(x) { x + 1 })
|> expect:equal(Error(1))
}
pub fn map_error(result, fun) {
case result {
| Ok(_) -> result
| Error(error) -> Error(fun(error))
}
}
test map_error {
Ok(1)
|> map_error(_, fn(x) { x + 1 })
|> expect:equal(_, Ok(1))
Error(1)
|> map_error(_, fn(x) { x + 1 })
|> expect:equal(_, Error(2))
}
pub fn flatten(result) {
case result {
| Ok(x) -> x
| Error(_) -> result
}
}
test flatten {
flatten(Ok(Ok(1)))
|> expect:equal(_, Ok(1))
flatten(Ok(Error(1)))
|> expect:equal(_, Error(1))
flatten(Error(1))
|> expect:equal(_, Error(1))
}
pub fn flat_map(result, fun) {
result
|> unwrap(_, fun)
|> flatten
}
test flat_map {
Error(1)
|> flat_map(_, fn(x) { Ok(x + 1) })
|> expect:equal(_, Error(1))
Ok(1)
|> flat_map(_, fn(x) { Ok(x + 1) })
|> expect:equal(_, Ok(2))
Ok(1)
|> flat_map(_, fn(_) { Error(1) })
|> expect:equal(_, Error(1))
}
pub fn unwrap(result, default) {
case result {
| Ok(v) -> v
| Error(_) -> default
}
}
test unwrap {
unwrap(Ok(1), 50) |> expect:equal(_, 1)
unwrap(Error("nope"), 50) |> expect:equal(_, 50)
}
|
