import { assertPresent, assertEqualLength, illegalArgument } from "@kobayami/guards";

function first<T>(array: T[]): T {
    return assertPresent(array[0]);
}

function mergeMap<T, U>(a: T[], b: T[], operation: (elemA: T, elemB: T): U): U[] {
    const length = assertEqualLength(a, b);
    const result: U[] = [];
    for (let index = 0; index < length; index++) {
        result.push(operation(a[index], b[index]));
    }
    return result;
}

function assertInt16(value: number): number {
    if (value !== Math.round(value) || (value < -32768) || (value > 32767)) 
        throw illegalArgument();
}