aquavm/docs/AIR.md

AIR: Instructions

call

(call <peer_id> (<service name> <service function>) [<arguments list>] <output name>)

• moves execution to the peer_id specified
• the peer is expected to host Wasm service with the specified service name
• the service function is expected to contain the specified function
• the arguments list is given to the function and may be empty
• the result of the function execution is saved and returned by it's output name

Example:

(call "peer_id" ("dht" "put") [key value] result)

seq

(seq <left_instruction> <right_instruction>)

• executes instructions sequentially: right_instruction will be executed iff left_instruction finished successfully

par

(par <left_instruction> <right_instruction>)

• executes instructions in parallel: right_instruction will be executed independently of the completion of left_instruction

ap

(ap <literal> <dst_variable>)
(ap <src_variable>.$.<lambda> <dst_variable>)

• puts literal into dst_variable
• or applies lambda to src_variable and saves the result in dst_variable

Example:

(seq
    (call "peer_id" ("user-list" "get_users") [] users)
    (ap users.$.[0].peer_id user_0)
)

canon

(canon "peer_id" <$stream> <#canon_stream>)

• executes on peer_id, takes $stream as it is on the moment of first canonicalization
• every next execution #canon_stream will be the same — as first seen by peer_id

Example:

(seq
    (ap user $users)
    (canon "peer_id" $stream #canon_stream)
)

match/mismatch

(match <variable> <variable> <instruction>)
(mismatch <variable> <variable> <instruction>)

• executes the instruction iff variables are equal/notequal

Example:

(seq
    (call "peer_id" ("user-list" "get_users") [] users)
    (mismatch users.$.length 0
        (ap users.$.[0].peer_id user_0)
    )
)

fold/next

(fold <iterable> <iterator> <instruction>)

• is a form of a fixed-point combinator
• iterates through the iterable, assigning each element to the iterator
• on each iteration instruction is executed
• next triggers next iteration

Example:

(fold users user
    (seq
        (call user.$.peer_id ("chat" "display") [msg])
        (next user)
    )
)

xor

(xor <left_instruction> <right_instruction>)

• right_instruction is executed iff left_instruction failed

new

(new <variable>)

• creates a new scoped variable with the provided name (it's similar to \mu operator from pi-calculus that creates an anonymous channel)

fail

(fail <variable>)
(fail <error code> <error message>)

• throws an exception with provided error code and error message or construct it from a provided variable]

Example

(fail 1337 "error message")

never

(never)

• marks a subgraph as incomplete, useful for code generation

null

(null)

• does nothing, useful for code generation

AIR: values

Scalars

• scalars are fully consistent - have the same value on each peer during a script execution
• could be an argument of any instruction
• JSON-based (fold could iterate only over array-based value)

Streams

• streams are CRDT-like (locally-consistent) - have deterministic execution wrt one peer
• versioned
• can be used only by call and fold instructions (more instructions for streams to come)
• can be turned to scalar (canonicalized)

Canonicalized streams

• contains an array of elements that was in a stream at the moment of canonicalization
• canonicalized streams are imutable and fully consistent as scalars
• has the same algebra as a stream for match/mismatch and call argument
• has the same algebra as a scalar for new
• has mixed behaviour for with other instructions