Scan and sort

main.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

type Liner interface {
	Process(string)
	PrintValues()
}

type ScoreProcessor struct {
	Map map[int][]string
}

func (p *ScoreProcessor) Process(s string) {
	b := strings.Split(s, ",")
	name := strings.TrimSpace(b[0])
	score, err := strconv.Atoi(strings.TrimSpace(b[1]))
	if err == nil && score >= 90 {
		if p.Map[score] == nil {
			p.Map[score] = make([]string, 0)
		}

		p.Map[score] = append(p.Map[score], name)
	}
}

func (p *ScoreProcessor) PrintValues() {
	for i := 90; i <= 100; i++ {
		for _, v := range p.Map[i] {
			fmt.Printf("%s - %d\n", v, i)
		}
	}
}

func main() {
	fn := os.Args[1]

	l := ScoreProcessor{
		Map: make(map[int][]string, 0),
	}
	err := LineByLine(fn, &l)
	if err != nil {
		fmt.Printf("error lining file: %v\n", err)
		os.Exit(1)
	}

	os.Exit(0)
}

func LineByLine(fn string, l Liner) error {
	f, err := os.Open(fn)
	defer f.Close()
	if err != nil {
		return err
	}

	s := bufio.NewScanner(f)

	for s.Scan() {
		t := s.Text()
		if s.Err() != nil {
			return err
		}

		if len(t) == 0 {
			break
		}

		l.Process(t)
	}

	l.PrintValues()

	return nil
}