roc/examples/parser/parse-movies-csv.roc
2024-04-13 12:28:16 +02:00

68 lines
2.4 KiB
Text

app "example"
packages {
pf: "https://github.com/roc-lang/basic-cli/releases/download/0.9.0/oKWkaruh2zXxin_xfsYsCJobH1tO8_JvNkFzDwwzNUQ.tar.br",
parser: "https://github.com/lukewilliamboswell/roc-parser/releases/download/0.5.2/9VrPjwfQQ1QeSL3CfmWr2Pr9DESdDIXy97pwpuq84Ck.tar.br",
}
imports [
pf.Stdout,
pf.Stderr,
pf.Task.{ Task },
parser.Core.{ Parser, map, keep },
parser.String.{ strFromUtf8 },
parser.CSV.{ CSV },
]
provides [main] to pf
input : Str
input = "Airplane!,1980,\"Robert Hays,Julie Hagerty\"\r\nCaddyshack,1980,\"Chevy Chase,Rodney Dangerfield,Ted Knight,Michael O'Keefe,Bill Murray\""
main : Task {} *
main =
when CSV.parseStr movieInfoParser input is
Ok movies ->
moviesString =
movies
|> List.map movieInfoExplanation
|> Str.joinWith ("\n")
nMovies = List.len movies |> Num.toStr
Stdout.line "$(nMovies) movies were found:\n\n$(moviesString)\n\nParse success!\n"
Err problem ->
when problem is
ParsingFailure failure ->
Stderr.line "Parsing failure: $(failure)\n"
ParsingIncomplete leftover ->
leftoverStr = leftover |> List.map strFromUtf8 |> List.map (\val -> "\"$(val)\"") |> Str.joinWith ", "
Stderr.line "Parsing incomplete. Following leftover fields while parsing a record: $(leftoverStr)\n"
SyntaxError error ->
Stderr.line "Parsing failure. Syntax error in the CSV: $(error)"
MovieInfo := { title : Str, releaseYear : U64, actors : List Str }
movieInfoParser =
CSV.record (\title -> \releaseYear -> \actors -> @MovieInfo { title, releaseYear, actors })
|> keep (CSV.field CSV.string)
|> keep (CSV.field CSV.u64)
|> keep (CSV.field actorsParser)
actorsParser =
CSV.string
|> map \val -> Str.split val ","
movieInfoExplanation = \@MovieInfo { title, releaseYear, actors } ->
enumeratedActors = enumerate actors
releaseYearStr = Num.toStr releaseYear
"The movie '$(title)' was released in $(releaseYearStr) and stars $(enumeratedActors)"
enumerate : List Str -> Str
enumerate = \elements ->
{ before: inits, others: last } = List.split elements (List.len elements - 1)
last
|> List.prepend (inits |> Str.joinWith ", ")
|> Str.joinWith " and "