json - Why do we need to explicitly use the implicit method on map value? -

this working example:

import spray.json._  trait jsonsupport {    implicit def string2jsvalue(s: string): jsvalue = {     jsstring(s)   }    implicit def map2jsobject(m: map[string, jsvalue]): jsobject = {     jsobject(m)   }    implicit def mapstring2jsobject(m: map[string, string]): jsobject = {     jsobject(m.map {       case (k,v) => (k,string2jsvalue(v))     })   }  } 

as stands now, working. if replace

implicit def mapstring2jsobject(m: map[string, string]): jsobject = {   jsobject(m.map {     case (k,v) => (k,string2jsvalue(v))   }) } 

with

implicit def mapstring2jsobject(m: map[string, string]): jsobject = {   jsobject(m) } 

then following error occurs:

expected: map[string, jsvalue], actual: map[string, string]

why implicit method not doing work , need call implicitly?

is possible use implicits in way such there no need write implicit methods every possible nesting of map? e.g.:

implicit def map1string2jsobject(m: map[string, string]): jsobject implicit def map2string2jsobject(m: map[string, map[string, string]]): jsobject implicit def map3string2jsobject(m: map[string, map[string, map[string, string]]]): jsobject ... 

in line case (k,v) => (k,v) haven't specified result of case should other (string,string). force implicit conversion, write:

case (k,v) => (k,v:jsvalue)