A Cap'n Proto message, parametrized over its mutability.

A segment in a Cap'n Proto message.

Mutability is used as a type parameter (with the DataKinds extension) to indicate the mutability of some values in this library; Const denotes an immutable value, while Mut s denotes a value that can be mutated in the scope of the state token s.

hPutMsg handle msg writes msg to handle. If there is an exception, it will be an IOError raised by the underlying IO libraries.

hGetMsg handle limit reads a message from handle that is at most limit 64-bit words in length.

Equivalent to hPutMsg stdout

Equivalent to hGetMsg stdin

readMessage read32 readSegment reads in a message using the monadic context, which should manage the current read position, into a message. read32 should read a 32-bit little-endian integer, and readSegment n should read a blob of n 64-bit words. The size of the message (in 64-bit words) is deducted from the traversal, limit which can be used to set the maximum message size.

writeMesage write32 writeSegment writes out the message. write32 should write a 32-bit word in little-endian format to the output stream. writeSegment should write a blob.

The maximum size of a segment supported by this libarary, in words.

The maximum number of segments allowed in a message by this library.

The maximum number of capabilities allowed in a message by this library.

encode encodes a message as a bytestring builder.

decode decodes a message from a bytestring.

The segments will not be copied; the resulting message will be a view into the original bytestring. Runs in O(number of segments in the message).

Convert a segment to a byte string. O(1)

Convert a ByteString to a segment. O(1)

Return the underlying storage of a mutable segment, as a vector.

Note that the elements of the vector will be stored in little-endian form, regardless of CPU endianness. This is a low level function that you should probably not use.

empty is an empty message, i.e. a minimal message with a null pointer as its root object.

Create a message from a single segment.

A Message is a (possibly read-only) capnproto message. It is parameterized over a monad in which operations are performed.

getCap message index gets the capability with the given index from the message. throws BoundsError if the index is out of bounds.

getCapTable gets the capability table from a ConstMsg.

getWord gets the word referred to by the WordPtr

Return the total number of words in the message, i.e. the sum of the results of numWords on all segments.

newMessage sizeHint allocates a new empty message, with a single segment having capacity sizeHint. If sizeHint is Nothing, defaults to a sensible value.

A pointer to a location in a message. This encodes the same information as a WordAddr, but also includes direct references to the segment and message, which can improve performance in very low-level code.

alloc size allocates size words within a message. it returns the starting address of the allocated memory, as well as a direct reference to the segment. The latter is redundant information, but this is used in low-level code where this can improve performance.

Like alloc, but the second argument allows the caller to specify the index of the segment in which to allocate the data. Returns Nothing if there is insufficient space in that segment..

newSegment msg sizeHint allocates a new, initially empty segment in msg with a capacity of sizeHint words. It returns the a pair of the segment number and the segment itself. Amortized O(1).

setSegment message index segment sets the segment at the given index in the message.

write segment index value writes a value to the 64-bit word at the provided index. Consider using setWord on the message, instead of calling this directly.

setCap message index cap sets the sets the capability at index in the message's capability table to cap. If the index is out of bounds, a BoundsError will be thrown.

appendCap appends a new capabilty to the end of a message's capability table, returning its index.

WriteCtx is the context needed for most write operations.

A reference to a capability, which may be live either in the current vat or elsewhere. Holding a client affords making method calls on a capability or modifying the local vat's reference count to it.

A null client. This is the only client value that can be represented statically. Throws exceptions in response to all method calls.

withCapTable replaces the capability table in the message.