## AIR: Instructions ### call ```wasm (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: ```wasm (call "peer_id" ("dht" "put") [key value] result) ``` ### seq ```wasm (seq <left_instruction> <right_instruction>) ``` - executes instructions sequentially: `right_instruction` will be executed iff `left_instruction` finished successfully ### par ```wasm (par <left_instruction> <right_instruction>) ``` - executes instructions in parallel: `right_instruction` will be executed independently of the completion of `left_instruction` ### ap ```wasm (ap <literal> <dst_variable>) (ap <src_variable>.$.<lambda> <dst_variable>) ``` - puts `literal` into `dst_variable` - or applies `lambda` to `src_variable` and saves the result in `dst_variable` Example: ```wasm (seq (call "peer_id" ("user-list" "get_users") [] users) (ap users.$.[0].peer_id user_0) ) ``` ### canon ```wasm (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: ```wasm (seq (ap user $users) (canon "peer_id" $stream #canon_stream) ) ``` ### match/mismatch ```wasm (match <variable> <variable> <instruction>) (mismatch <variable> <variable> <instruction>) ``` - executes the instruction iff variables are equal/notequal Example: ```wasm (seq (call "peer_id" ("user-list" "get_users") [] users) (mismatch users.$.length 0 (ap users.$.[0].peer_id user_0) ) ) ``` ### fold/next ```wasm (fold <iterable> <iterator> <instruction>) ``` - is a form of a fixed-point combinator - iterates through the `iterable`, assigning each element to the `iterator` - on each iteration `instruction` is executed - `next` triggers next iteration Example: ```wasm (fold users user (seq (call user.$.peer_id ("chat" "display") [msg]) (next user) ) ) ``` ### xor ```wasm (xor <left_instruction> <right_instruction>) ``` - `right_instruction` is executed iff `left_instruction` failed ### new ```wasm (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 ```wasm (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 ```wasm (fail 1337 "error message") ``` ### never ```wasm (never) ``` - marks a subgraph as incomplete, useful for code generation ### null ```wasm (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