Hex color parsing using parser combinator

parser-combinator-with-error-handling.ts

const match_char = (c: string) => (input: string) => {
    if (input[0] === c) {
        return {success: true, value: input[0], rest: input.slice(1), error: null}
    }
    return {success: false, value: null, rest: input, error: new Error("Expected " + c + " but found " + input[0] + "\nRemaining: " + input )}
};

const any_char = (input: string) => {
    if (typeof input[0] === 'string') {
        return {success: true, value: input[0], rest: input.slice(1), error: null}
    }
    return {success: false, value: null, rest: input, error: new Error("Expected a character, found not a char\nRemaining: " + input )}
};

const combine = (parsers: Array<any>) => (input: string) => {
    let next = input;
    let result = [];
    for (let i = 0; i < parsers.length; i++) {
        const parser: any = parsers[i];
        const { success, value, rest, error } = parser(next);
        if (!success) {
            return { success, value, rest, error };
        } else {
            result.push(value);
        }
        next = rest;
    }
    return { success: true, value: result, rest: next, error: null };
};

const hex_primitive = (s: string) => {
    let {success, value, rest, error} = combine([ any_char, any_char ])(s);
    if (success) {
        return { success, value: value.join(""), rest, error };
    } else {
        return { success, value, rest, error };
    }
}

const hex_color = (s: string) => {
    let {success, value, rest, error} = combine([ match_char('#'), hex_primitive, hex_primitive, hex_primitive ])(s);
    if (success) {
        let colors = value.slice(1).map(hex => parseInt(hex, 16));
        return colors;
    } else {
        throw error;
    }
};

hex_color("#5A4B3C"); // Should success
hex_color("5A4B3C"); // Expected '#' found '5'
hex_color("#5AB3C"); // Expected a character, found not a character

parser-combinator.ts

const match_char = (c: string) => (input: string) => {
    if (input[0] === c) {
        return {success: true, value: input[0], rest: input.slice(1)}
    }
    return {success: false, value: null, rest: input}
};

const any_char = (input: string) => {
    if (typeof input[0] === 'string') {
        return {success: true, value: input[0], rest: input.slice(1)}
    }
    return {success: false, value: null, rest: input}
};

const combine = (parsers: Array<any>) => (input: string) => {
    let next = input;
    let result = [];
    for (let i = 0; i < parsers.length; i++) {
        const parser: any = parsers[i];
        const { success, value, rest } = parser(next);
        if (!success) {
            return { success, value, rest };
        } else {
            result.push(value);
        }
        next = rest;
    }
    return { success: true, value: result, rest: next };
};

const hex_primitive = (s: string) => {
    let {success, value, rest} = combine([ any_char, any_char ])(s);
    return { success: success, value: value.join(""), rest: rest };
}

const hex_color = (s: string) => {
    let {success, value, rest} = combine([ match_char('#'), hex_primitive, hex_primitive, hex_primitive ])(s);
    let colors = value.slice(1).map(hex => parseInt(hex, 16));
    return colors;
};

hex_color("#5A4B3C"); // [90, 75, 60]