97 lines
2.1 KiB
Gleam
97 lines
2.1 KiB
Gleam
import gleam/dict
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import gleam/io
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import gleam/list
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import gleam/string
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import simplifile
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const history_file = ".history"
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@external(erlang, "io", "get_line")
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fn get_line(prompt: String) -> String
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@external(erlang, "erlang", "halt")
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fn halt(code: Int) -> Nil
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type Command {
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Command(name: String, description: String, run: fn(List(Command)) -> Nil)
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}
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fn clean(_cmds: List(Command)) -> Nil {
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case simplifile.delete(history_file) {
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Ok(Nil) -> Nil
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Error(e) -> io.println(simplifile.describe_error(e))
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}
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}
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fn history(_cmds: List(Command)) -> Nil {
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case simplifile.read(history_file) {
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Ok(content) -> io.print(content)
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Error(e) -> io.println(simplifile.describe_error(e))
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}
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}
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fn help(cmds: List(Command)) -> Nil {
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io.println("Available commands:")
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list.each(cmds, fn(cmd) {
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io.println(" " <> cmd.name <> " - " <> cmd.description)
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})
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}
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fn exit(_cmds: List(Command)) -> Nil {
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halt(0)
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}
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fn build_commands() -> List(Command) {
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[
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Command("clean", "delete history", clean),
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Command("help", "show this help", help),
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Command("history", "show history", history),
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Command("exit", "quit the program", exit),
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]
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}
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fn commands_dict(
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cmds: List(Command),
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) -> dict.Dict(String, fn(List(Command)) -> Nil) {
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list.fold(cmds, dict.new(), fn(acc, cmd) {
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dict.insert(acc, cmd.name, cmd.run)
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})
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}
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fn append_history(cmd: String) -> Nil {
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case simplifile.append(history_file, cmd <> "\n") {
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Ok(Nil) -> Nil
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Error(e) -> io.println(simplifile.describe_error(e))
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}
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}
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fn repl_loop(cmds: List(Command)) -> a {
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let input = get_line("repl> ") |> string.trim
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let cmd = string.lowercase(input)
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case cmd {
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"" -> Nil
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_ -> {
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input |> append_history
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case dict.get(commands_dict(cmds), cmd) {
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Ok(func) -> func(cmds)
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Error(_) -> io.println(input <> ": unknown command")
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}
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}
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}
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repl_loop(cmds)
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}
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pub fn main() -> Nil {
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let cmds = build_commands()
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case simplifile.is_file(history_file) {
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Ok(True) -> repl_loop(cmds)
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_ ->
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case simplifile.create_file(history_file) {
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Ok(Nil) -> repl_loop(cmds)
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Error(e) -> io.println(simplifile.describe_error(e))
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}
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}
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}
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