A fasta parser in go lang

fastaParser.go

package main

import (
	"bytes"
	"fmt"
	"log"
	"os"
	"strings"
  "bufio"
  "io"
)

type fasta struct {
  id string
  desc string
  seq string
}

func build_fasta(header string, seq bytes.Buffer) (record fasta) {
  fields := strings.SplitN(header, " ", 2)

  if len(fields) > 1 {
    record.id = fields[0]
    record.desc = fields[1]
  }else{
    record.id = fields[0]
    record.desc = ""
  }

  record.seq = seq.String()

  return record
}

func parse(fastaFh io.Reader) chan fasta {

  outputChannel := make(chan fasta)

  scanner := bufio.NewScanner(fastaFh)
  // scanner.Split(bufio.ScanLines)
  header := ""
  var seq bytes.Buffer

  go func() {
    // Loop over the letters in inputString
    for scanner.Scan() {
      line := strings.TrimSpace(scanner.Text())
      if len(line) == 0 {
        continue
      }

      // line := scanner.Text()

      if line[0] == '>' {
        // If we stored a previous identifier, get the DNA string and map to the
        // identifier and clear the string
        if header != "" {
          // outputChannel <- build_fasta(header, seq.String())
          outputChannel <- build_fasta(header, seq)
          // fmt.Println(record.id, len(record.seq))
          header = ""
          seq.Reset()
        }

        // Standard FASTA identifiers look like: ">id desc"
        header = line[1:]
      } else {
        // Append here since multi-line DNA strings are possible
        seq.WriteString(line)
      }

    }

    outputChannel <- build_fasta(header, seq)

    // Close the output channel, so anything that loops over it
    // will know that it is finished.
    close(outputChannel)
  }()

  
  return outputChannel
}

func main() {

  fastaFh, err := os.Open(os.Args[1])
  if err != nil {
    log.Fatal(err)
  }
  defer fastaFh.Close()

	for record := range parse(fastaFh) {
		fmt.Println(record.id, len(record.seq), record.seq[:100])
	}
}