package constant type Month string var Months = []Month{ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December", } func (m Month) ToFrench() string { return map[Month]string{ "January": "Janvier", "February": "Février", "March": "Mars", "April": "Avril", "May": "Mai", "June": "Juin", "July": "Juillet", "August": "Août", "September": "Septembre", "October": "Octobre", "November": "Novembre", "December": "Décembre", }[m] }