JSON & Process Spawning

Wysna provides structured data serialization and process execution modules in its standard library: std/json and std/process.

JSON Handling (std/json)

The std/json module parses and serializes standard JSON data structures using the algebraic type json.Value and helper query functions.

Parsing and Querying JSON

import "std/json.wysna"

fn main() -> unit {
    let raw = "{\"name\":\"gateway\",\"enabled\":true}"

    let decoded = json.parse(raw) else err {
        print("JSON parse error at offset:", err.offset, err.message)
        return
    }

    # Query fields safely with json.get and typed extractors
    let name_value = json.get(decoded, "name") ?? json.null()
    print("Service name:", json.as_string(name_value) ?? "missing")

    # Serializing back to JSON text
    let output = json.stringify(decoded) else err {
        print("Serialization error:", err.message)
        return
    }
    print("Serialized:", output)
}

Available std/json Functions

• json.parse(source: str) -> json.Value ! json.JsonError: Parses raw JSON text.
• json.stringify(value: json.Value) -> str ! json.JsonError: Serializes a JSON tree into compact UTF-8 text.
• json.get(obj: json.Value, key: str) -> json.Value?: Retrieves a field from a JSON object.
• json.at(arr: json.Value, index: int) -> json.Value?: Retrieves an item by index from a JSON array.
• json.as_string(val: json.Value) -> str?: Extracts the underlying string value.
• json.as_bool(val: json.Value) -> bool?: Extracts the underlying boolean flag.
• json.null() -> json.Value: Returns a canonical JSON Null variant.

---

Process Spawning (std/process)

The std/process module executes external system binaries directly without an intermediate command shell. Arguments are passed as raw UTF-8 string vectors, preventing shell injection vulnerabilities.

import "std/process.wysna"

fn main() -> unit {
    # Arguments: executable, argv array, timeout in milliseconds (max 10 minutes)
    let exit_code = process.run("git", ["status", "--short"], 5000) else err {
        print("Failed to spawn process:", err.operation, "code:", err.code)
        return
    }

    print("Process exited with status:", exit_code)
}

Key security guarantees of process.run:

• No Shell Interpolation: The executable is invoked directly via OS process primitives (execvp / CreateProcess).
• Bounded Execution: Timeouts are strictly enforced (between 1ms and 600,000ms).
• Inherited Streams: Standard output and standard error are inherited from the parent process.