# ExperimentalInternetComputer
Low-level interface to the Internet Computer.

**WARNING:** This low-level API is **experimental** and likely to change or even disappear.

## Value `call`
``` motoko no-repl
let call : (canister : Principal, name : Text, data : Blob) -> async (reply : Blob)
```

Calls ``canister``'s update or query function, `name`, with the binary contents of `data` as IC argument.
Returns the response to the call, an IC _reply_ or _reject_, as a Motoko future:

* The message data of an IC reply determines the binary contents of `reply`.
* The error code and textual message data of an IC reject determines the future's `Error` value.

Note: `call` is an asynchronous function and can only be applied in an asynchronous context.

Example:
```motoko no-repl
import IC "mo:base/ExperimentalInternetComputer";
import Principal "mo:base/Principal";

let ledger = Principal.fromText("ryjl3-tyaaa-aaaaa-aaaba-cai");
let method = "decimals";
let input = ();
type OutputType = { decimals : Nat32 };

let rawReply = await IC.call(ledger, method, to_candid(input)); // serialized Candid
let output : ?OutputType = from_candid(rawReply); // { decimals = 8 }
```

[Learn more about Candid serialization](https://internetcomputer.org/docs/current/developer-docs/build/cdks/motoko-dfinity/language-manual#candid-serialization)

## Function `countInstructions`
``` motoko no-repl
func countInstructions(comp : () -> ()) : Nat64
```

Given computation, `comp`, counts the number of actual and (for IC system calls) notional WebAssembly
instructions performed during the execution of `comp()`.

More precisely, returns the difference between the state of the IC instruction counter (_performance counter_ `0`) before and after executing `comp()`
(see [Performance Counter](https://internetcomputer.org/docs/current/references/ic-interface-spec#system-api-performance-counter)).

NB: `countInstructions(comp)` will _not_ account for any deferred garbage collection costs incurred by `comp()`.

Example:
```motoko no-repl
import IC "mo:base/ExperimentalInternetComputer";

let count = IC.countInstructions(func() {
  // ...
});
```