052 interpreter identity result

// Test: Interpreter identity branch constructor (result s) and discard (_)

~import std/runtime
~import std/interpreter
~import std/io

const std = @import("std");

// Event with identity branch payload
~pub event add { a: i64, b: i64 }
| sum i64

~add => sum a + b

~std/runtime:register(scope: "test") {
    add
}

const TEST_SOURCE_IDENTITY =
    \\~add(a: 3, b: 4)
    \\| sum s |> result s
;

const TEST_SOURCE_BRANCH =
    \\~add(a: 3, b: 4)
    \\| sum s |> result s.Branch
;

const TEST_SOURCE_DISCARD =
    \\~add(a: 3, b: 4)
    \\| sum s |> _
;

~std/runtime:get-scope(name: "test")
| scope s |> std/interpreter:run(source: TEST_SOURCE_IDENTITY, s.dispatcher)
    | result r |> std/interpreter:value.stringify(r.value)
        | json j |> std/io:print.ln("IDENTITY {{ j:s }}")
    | exhausted e |> std/io:print.ln("EXHAUSTED: {{ e.last_event:s }}")
    | parse-error e |> std/io:print.ln("PARSE ERROR: {{ e.message:s }}")
    | validation-error e |> std/io:print.ln("VALIDATION ERROR: {{ e:s }}")
    | dispatch-error e |> std/io:print.ln("DISPATCH ERROR: {{ e.message:s }}")
| not-found |> std/io:print.ln("SCOPE NOT FOUND")

~std/runtime:get-scope(name: "test")
| scope s |> std/interpreter:run(source: TEST_SOURCE_BRANCH, s.dispatcher)
    | result r |> std/interpreter:value.stringify(r.value)
        | json j |> std/io:print.ln("BRANCH {{ j:s }}")
    | exhausted e |> std/io:print.ln("EXHAUSTED: {{ e.last_event:s }}")
    | parse-error e |> std/io:print.ln("PARSE ERROR: {{ e.message:s }}")
    | validation-error e |> std/io:print.ln("VALIDATION ERROR: {{ e:s }}")
    | dispatch-error e |> std/io:print.ln("DISPATCH ERROR: {{ e.message:s }}")
| not-found |> std/io:print.ln("SCOPE NOT FOUND")

~std/runtime:get-scope(name: "test")
| scope s |> std/interpreter:run(source: TEST_SOURCE_DISCARD, s.dispatcher)
    | result r |> std/io:print.ln("DISCARD {{ r.value.branch:s }}")
    | exhausted e |> std/io:print.ln("EXHAUSTED: {{ e.last_event:s }}")
    | parse-error e |> std/io:print.ln("PARSE ERROR: {{ e.message:s }}")
    | validation-error e |> std/io:print.ln("VALIDATION ERROR: {{ e:s }}")
    | dispatch-error e |> std/io:print.ln("DISPATCH ERROR: {{ e.message:s }}")
| not-found |> std/io:print.ln("SCOPE NOT FOUND")