bf-to-midi because why not

bf-to-midi.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"time"

	"github.com/rakyll/portmidi"
)

var runeToNote = map[rune]int64{
	'>': 60,
	'<': 62,
	'+': 64,
	'-': 65,
	'.': 67,
	',': 69,
	'[': 71,
	']': 72,
}

const (
	minVelocity = int64(50)
	maxVelocity = int64(75)
)

func main() {
	portmidi.Initialize()
	defer portmidi.Terminate()

	s, err := portmidi.NewOutputStream(portmidi.DeviceID(3), 1024, 0)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	defer s.Close()

	var previousRune rune
	velocity := minVelocity
	reader := bufio.NewReader(os.Stdin)
	for {
		currentRune, _, err := reader.ReadRune()
		if err != nil {
			if err == io.EOF {
				os.Exit(0)
			}
			fmt.Println(err)
			os.Exit(1)
		}
		fmt.Printf("%c", currentRune)

		if currentRune == previousRune && velocity < maxVelocity {
			velocity++
			continue
		}

		note, ok := runeToNote[previousRune]
		if ok {
			err = s.WriteShort(0x90, note, velocity) // Turn on note on channel 1
			if err != nil {
				fmt.Println(err)
				os.Exit(1)
			}

			time.Sleep(100 * time.Millisecond)

			err = s.WriteShort(0x80, note, 0) // Turn off note on channel 1
			if err != nil {
				fmt.Println(err)
				os.Exit(1)
			}
		}

		previousRune = currentRune
		velocity = minVelocity
	}
}