std.io.read

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Functions and types for working with Readers.

Types

#[implicit]
type Read a = {
    read : a -> Int -> IO (Option (Array Byte)),
    read_to_end : a -> IO (Array Byte)
}

Allows reading bytes from a. Generally, reading from a reader advances its internal cursor. This means that multiple read calls with the same arguments usually do not return the same value.

type Buffered r = { reader : r, buf : Reference (Array Byte), capacity : Int }

Wraps a reader to provide buffering. Buffering is more efficient when performing many small reads, because it avoids many costly reads from the underlying reader.

If you are reading all data at once, buffering is not necessary.

Values

let read ?read : forall a . [Read a] -> a -> Int -> IO (Option (Array Byte))

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Tries to read num_bytes byte from the reader. If the reader has reached end of file or num_bytes was zero, None will be returned. Otherwise, an array containing as many bytes as could be read will be returned. The length of the array is guaranteed to be in the range [1, num_bytes].

Reaching end of file means that this reader will most likely not produce more bytes. It may produce more in the future.

let read_to_end ?read : forall a . [Read a] -> a -> IO (Array Byte)

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Read all bytes until end of file is encountered.

let read_to_string reader : forall a . [Read a] -> a -> IO (Option String)

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Read all bytes until end of file is encountered into a String. Returns None if the read bytes are not valid UTF-8.

let default_read_to_end read : forall a . (a -> Int -> IO (Option (Array Byte))) -> a -> IO (Array Byte)

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Constructs a read_to_end function from a read function. If it is more efficient, implementors of Read should provide their own, specialized version.

let buffered reader : forall a . [Read a] -> a -> Buffered a

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Wraps reader in a Buffered reader to provide buffering.

let buffered_with_capacity capacity reader : forall a . [Read a] -> Int -> a -> Buffered a

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Wraps reader in a Buffered reader to provide buffering with the specified buffer capacity.

#[implicit]
let read_buffered : forall r . [Read r] -> Read (Buffered r)

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Allows reading bytes from a. Generally, reading from a reader advances its internal cursor. This means that multiple read calls with the same arguments usually do not return the same value.

#[implicit]
let disposable_buffered : forall r . [Disposable r] -> Disposable (Buffered r)

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A resource that has to be released after use, for example a file handle or a database connection.