I/O

The standard library needs to provide adequate possibilities to enable input/output operations.

We compare Fuzion and other languages by looking at the facilities for reading from files, stdin, or sockets. The situation is very similar for writing.

Current State of I/O in Fuzion

The io.file.read effect currently provides just read_all which just reads all of the given file into a byte array.

io.file.stdin currently provides read, which reads n codepoints (!) into a string, and read_line, which reads a line into a string. A pull request adds reading of single bytes, multiple bytes and single codepoints.

Since the goal of Fuzion is to unify different concepts, this situation is obviously not ideal.

Comparison with other languages

We compare the situation above to the situation in Go and Rust. Both handle I/O quite similarly.

Go provides two relevant low-level interfaces: io.Reader and io.ByteReader. io.Reader provides a single function Read which can be used to read a given number of bytes, while io.ByteReader provides a function ReadByte which reads just a single byte. This comment on GitHub explains the difference of io.Reader and io.ByteReader.

To get the more useful higher-level operations of reading lines, or codepoints (they are called "runes" in Go), or just to have buffering, Go provides a wrapper called bufio.Reader. This works with any io.Reader.

Rust does this similarly, there is a Read trait which requires a defined method read which also tries to read a given number of bytes. The Read trait implements some default methods based on read, e.g. an iterator for the bytes. Similarly to Go, if you want to use some useful higher-level methods, you can use a BufReader, which is similar to the bufio.Reader. Note that Rust does not seem to provide a way to read a given number of codepoints. (It is implemented by a third-party library).

Conclusion for Fuzion

The way Go and Rust do I/O seems pretty intuitive because developers deal with e.g. network the same way they deal with files or stdin. This is also what we want to do in Fuzion. However, the concepts will need to be adapted to Fuzion's particular features, specifically effects.

It is not clear whether it is necessary to provide codepoint-oriented I/O in the standard library.