io/io.bend source

io/io.bend on the hub · documented module

import Base# grounds-io: whole-file reads, as text or as raw bytes.##   import ../io/io.bend as Io#   Io.read_text(path, limit)   # Got{text}, or TooBig{size} past limit bytes#   Io.read_bytes(path)         # the bytes as they are, 0..255## A path is used once: a String used twice is shared, and sharing any# String makes every String in the program reference counted.# a read text, or the file's size when it was over the limittype Read is Data:  Got{text: String}  TooBig{size: U32}def over(limit: Maybe<&2, U32>, +n: U32) -> Bool:  match limit:    case None{}:      False{}    case Some{x}:      U32.is_gt(n, x)law text.close:  for m: File & Result<&1, &1, (U32 & String), String>  IO(Read)def text.close(m):  (f, r) = m  do IO<Read>:    text : String <- IO.pass(String, r)    x : Unit <- File.close(f)    return Got{text}def text.check(big: Bool, f: File, +n: U32) -> IO(Read):  match big:    case True{}:      do IO<Read>:        x : Unit <- File.close(f)        return TooBig{n}    case False{}:      do IO<Read>:        t : File & Result<&1, &1, (U32 & String), String> <- File.read(f, (n + 1 : U32))        text.close(t)law text.size:  for m: File & Result<&1, &1, (U32 & String), U32>  for limit: Maybe<&2, U32>  IO(Read)def text.size(m, limit):  (f, r) = m  do IO<Read>:    +n : U32 <- IO.pass(U32, r)    text.check(over(limit, n), f, n)# the file as text, decoded by the runtime, which turns each bad UTF-8# sequence into U+FFFD; None reads any sizedef read_text(path: String, limit: Maybe<&2, U32>) -> IO(Read):  do IO<Read>:    f : File <- IO.try(File, File.open(path, "r"))    m : File & Result<&1, &1, (U32 & String), U32> <- File.size(f)    text.size(m, limit)law bytes.close:  for m: File & Result<&1, &1, (U32 & String), List<&2, U32>>  IO(List<&2, U32>)def bytes.close(m):  (f, r) = m  do IO<List<&2, U32>>:    bs : List<&2, U32> <- IO.pass(List<&2, U32>, r)    x : Unit <- File.close(f)    return bslaw bytes.size:  for m: File & Result<&1, &1, (U32 & String), U32>  IO(List<&2, U32>)def bytes.size(m):  (f, r) = m  do IO<List<&2, U32>>:    n : U32 <- IO.pass(U32, r)    t : File & Result<&1, &1, (U32 & String), List<&2, U32>> <- File.read_bytes(f, (n + 1 : U32))    bytes.close(t)# the file's bytes as they are (0..255), one list cell eachdef read_bytes(path: String) -> IO(List<&2, U32>):  do IO<List<&2, U32>>:    f : File <- IO.try(File, File.open(path, "r"))    m : File & Result<&1, &1, (U32 & String), U32> <- File.size(f)    bytes.size(m)