Cannot find implementation for functions

[fewwwww]

In BigInt class of graph-ts library, the operators rely on certain functions.

However, only host interfaces are defined, but I cannot find the implementation for those functions.

/** Host interface for BigInt arithmetic */
export declare namespace bigInt {
  function plus(x: BigInt, y: BigInt): BigInt;
  function minus(x: BigInt, y: BigInt): BigInt;
  function times(x: BigInt, y: BigInt): BigInt;
  function dividedBy(x: BigInt, y: BigInt): BigInt;
  function dividedByDecimal(x: BigInt, y: BigDecimal): BigDecimal;
  function mod(x: BigInt, y: BigInt): BigInt;
  function pow(x: BigInt, exp: u8): BigInt;
  function fromString(s: string): BigInt;
  function bitOr(x: BigInt, y: BigInt): BigInt;
  function bitAnd(x: BigInt, y: BigInt): BigInt;
  function leftShift(x: BigInt, bits: u8): BigInt;
  function rightShift(x: BigInt, bits: u8): BigInt;
}

Also, conversion.ts has interface, but no implementation.

[maoueh]

@fewwwww There is no implementations because those are WASM intrinsics, which is essentially the signature of functions that you can use in your AssemblyScript code that are provided by the host environment, so the entity actually executing the WASM compiled from your AssemblyScript source code.

In The Graph case, the host environment is graph-node which is the one responsible for executing your WASM code. You can find most of the intrinsics implementation at https://github.com/graphprotocol/graph-node/blob/master/runtime/wasm/src/host_exports.rs for example the bigInt#plus method implementation is defined at https://github.com/graphprotocol/graph-node/blob/master/runtime/wasm/src/host_exports.rs#L475.

[fewwwww]

Thanks for the reply!

I have a follow-up question on that: why are they designed to be WASM intrinsics? Is it due to the performance of AssemblyScript?

[maoueh]

Indeed usually it's for speed reason that intrinsics are used. Maybe here it was because back in the days, there were AssemblyScript limitations preventing efficient implementation.

I'm note quite sure to be honest what was the reasons when those were initially created.