builder.go

package main

import (
	"fmt"
	"strings"
)

type Clause interface {
	By() string
}

type ClauseFunc func() string
func (c ClauseFunc) By() string {
	return c()
}

func By(field string, value interface{}) Clause {
	return ClauseFunc(func() string {
		return fmt.Sprintf("%s = %s", field, value)
	})
}

func ByID(value interface{}) Clause {
	return By("id", value)
}

func And(clauses ...Clause) Clause {
	return ClauseFunc(func() string {
		where := []string{}

		for _, clause := range clauses {
			where = append(where, clause.By())
		}
		
		return strings.Join(where, " AND ")
	})
}

func Select(clauses ...Clause) string {
	query := "SELECT * FROM blah WHERE "
	where := []string{}

	for _, clause := range clauses {
		where = append(where, clause.By())
	}
	
	return query + strings.Join(where, " AND ")
}

func main() {
	fmt.Println(
		Select(
			And(
				ByID(10), 
				By("name", "Claudemiro"),
			),
		),
	)
}