domain/architecture/system/effs/io.bend source

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import Base# V's I/O: running a program with its arguments (the effect below), and reading and writing files with# Base's File API.# ---- running a program ----# Temporary: bend-kit-process does this, but no Bend version runs both it (2.0.27 only) and bend-kit-files (2.0.28+).def Program.run(cmd: String, args: String) -> IO(Result<&1, &1, U32 & String, String>):  import "./program_run.c"  import "./program_run.js"def out_of(r: Result<&1, &1, U32 & String, String>) -> String:  match r:    case Done{out}:      out    case Fail{_}:      ""def ok_of(r: Result<&1, &1, U32 & String, String>) -> Bool:  match r:    case Done{_}:      True{}    case Fail{_}:      False{}# A program's standard output when it exits 0, else "".def run(cmd: String, args: List<&2, String>) -> IO(String):  do IO<String>:    r : Result<&1, &1, U32 & String, String> <- Program.run(cmd, String.join(args, "\u{1f}"))    return out_of(r)# Whether a program exits 0.def succeeds(cmd: String, args: List<&2, String>) -> IO(Bool):  do IO<Bool>:    r : Result<&1, &1, U32 & String, String> <- Program.run(cmd, String.join(args, "\u{1f}"))    return ok_of(r)def home() -> IO(String):  do IO<String>:    r : Result<&1, &1, U32 & String, String> <- IO.get_env("HOME")    return Result.default(&1, &1, U32 & String, String, r, "")# ---- reading a file: its text, or "" when it cannot be read ----def size_of(r: Result<&1, &1, U32 & String, U32>) -> U32:  match r:    case Done{n}:      n    case Fail{_}:      0def text_of(r: Result<&1, &1, U32 & String, String>) -> String:  match r:    case Done{t}:      t    case Fail{_}:      ""def read_done(r: File & Result<&1, &1, U32 & String, String>) -> IO(String):  match r:    case (f, got):      do IO<String>:        File.close(f)        return text_of(got)def read_sized(r: File & Result<&1, &1, U32 & String, U32>) -> IO(String):  match r:    case (f, n):      do IO<String>:        got : File & Result<&1, &1, U32 & String, String> <- File.read(f, size_of(n))        read_done(got)def read_opened(r: Result<&1, &1, U32 & String, File>) -> IO(String):  match r:    case Done{f}:      do IO<String>:        n : File & Result<&1, &1, U32 & String, U32> <- File.size(f)        read_sized(n)    case Fail{_}:      IO.pure(String, "")def read_head_opened(r: Result<&1, &1, U32 & String, File>, max: U32) -> IO(String):  match r:    case Done{f}:      do IO<String>:        got : File & Result<&1, &1, U32 & String, String> <- File.read(f, max)        read_done(got)    case Fail{_}:      IO.pure(String, "")# The first `max` bytes of a file ("" if unreadable): enough for what sits at its top, like imports.def read_head(path: String, max: U32) -> IO(String):  do IO<String>:    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")    read_head_opened(r, max)def read(path: String) -> IO(String):  do IO<String>:    r : Result<&1, &1, U32 & String, File> <- File.open(path, "r")    read_opened(r)# ---- writing a file ----def after_write(r: File & Result<&1, &1, U32 & String, Unit>) -> IO(Unit):  match r:    case (f, _):      File.close(f)def write_opened(r: Result<&1, &1, U32 & String, File>, text: String) -> IO(Unit):  match r:    case Done{f}:      do IO<Unit>:        w : File & Result<&1, &1, U32 & String, Unit> <- File.write(f, text)        after_write(w)    case Fail{_}:      IO.die(Unit, 1, "cannot write a file")def write(path: String, text: String) -> IO(Unit):  do IO<Unit>:    r : Result<&1, &1, U32 & String, File> <- File.open(path, "w")    write_opened(r, text)def keep_filled(c: Bool, x: String, rest: List<&2, String>) -> List<&2, String>:  match c:    case True{}:      x <> rest    case False{}:      rest# The trimmed, non-empty strings.def nonempty(xs: List<&2, String>) -> List<&2, String>:  match xs:    case []:      []    case +x <> rest:      keep_filled(Bool.not(String.is_empty(String.trim(x))), String.trim(x), nonempty(rest))