govim

#!/bin/bash
shopt -s extglob;

_isFlag() {
    case "${1}" in
        *(-)[${2}${2^^}] )
            return 0;
            ;;
        * )
            return 1;
            ;;
    esac;
}

_clear() {
    [ -e "${TMP}" ] &&
        rm "${TMP}";

    cat << EOF >> "${TMP}"
func main() {
    
}
EOF
}

_write() {
    [ -e "${FILE}" ] && rm "${FILE}";

    cat << EOF >> "${FILE}"
package main

import (
	"fmt"
	"bytes"
)

var (
    buffer bytes.Buffer
)

// Pass to fmt.Println().
func print(a ...interface{}) {
    fmt.Println(a...)
}

// Pass to fmt.Printf().
func printf(format string, a ...interface{}) {
	fmt.Printf(format, a...)
}

// Concatenate strings together into one string.
func concat(slc ...string) string {
    b := bytes.NewBuffer(nil)
    defer b.Reset()
	for _, s := range slc {
		b.WriteString(s)
	}
	return b.String()
}

// Convert a string into a slice.
func slc(args ...string) []string {
	return args
}

EOF
    cat "${TMP}" >> "${FILE}";
}

_run() {
    "${VIM}" -n -X -c :wq "${FILE}";
    go run "${FILE}";
}

_edit() {
    "${VIM}" -c 'let g:go_fmt_command="gofmt" | let g:go_fmt_fail_silently=1 | star' +2 "${TMP}";
    _write;
}

declare -r VIM="vim";
#declare -r VIM="nvim";
declare -r FILE="govim.go";
declare -r TMP=".govimtmp.go";

pushd "${GOPATH}" &>/dev/null;

[ -n "${1}" ] ||
    _clear;

if _isFlag "${1}" "s"; then
    "${VIM}" "${FILE}";
    exit $?;
fi;

declare OLD="$(cat "${TMP}")";
_edit;

declare NEW="$(cat "${TMP}")";
[[ "${OLD}" != "${NEW}" || -n "${1}" ]] ||
    exit $?;
_run;

popd &>/dev/null;