Standard library

`std/fs`

import "std/fs"

Files.makeDir("build/reports")
writeFile("build/reports/summary.txt", "3 files\n")
appendFile("build/reports/summary.txt", "done\n")
for name in Files.list("build/reports") {
    var path = Files.join(["build/reports", name])
    print(name, len(readFile(path)), "characters")
}
Files.remove("build/reports")

File contents

Function	Result
`readFile(path)`	the whole file as a string; stops with a runtime error when it cannot be read
`writeFile(path, content)`	replaces the file with `content` (any value, formatted like `print`); `false` on failure
`appendFile(path, content)`	adds `content` at the end, creating the file; `false` on failure
`fileExists(path)`	whether something exists at `path`

Files are read and written as UTF-8 text. Check fileExists before reading a file that may be missing, or catch the problem where it is expected:

import "std/fs"

fun loadSettings(path: string): string {
    if (!fileExists(path)) {
        return "{}"
    }
    return readFile(path)
}

print(loadSettings("settings.json"))

`Files`

Function	Result
`Files.makeDir(path)`	creates the folder and any missing parents; `true` when it exists afterwards
`Files.remove(path)`	removes a file, or a folder with everything in it; `true` when nothing is left
`Files.rename(from, to)`	moves or renames a file or folder; `true` on success
`Files.copy(from, to)`	copies a file; `true` on success
`Files.list(path)`	the names in a folder, sorted, without the folder; `[]` if it cannot be read
`Files.isDir(path)`	whether `path` is an existing folder
`Files.isFile(path)`	whether `path` is an existing regular file
`Files.join(parts)`	the parts joined with `/`, skipping empty parts and doubled slashes

None of the Files functions stops the program: each reports failure through its result. Paths are relative to the working directory, which Process.setCwd changes. For splitting and normalizing paths (dirName, baseName, stem, extension, normalize, joinPath), see std/path in collections and paths.

In other backends

The functions behave the same on bvm, in native executables and in JavaScript (through Node's fs module). They are not available to programs built without the standard library (no-std).