(def units {:cm 100
            :mm 1000
            :m  1
            :km 1/1000})

(defn m-to-unit-helper [[k v]]
  (let [f (symbol (str "to-" (name k)))]
    `(defn ~f [m#] (* ~v m#))))

(defmacro m-to-units [units-map]
  (let [funcs (map m-to-unit-helper units-map)]
    `(do ~@funcs)))

; complains with: Don't know how to create ISeq from: clojure.lang.Symbol
(m-to-units units)

; To try and debug
(defn debug [units-map]
  (let [funcs (map m-to-unit-helper units-map)]
    (clojure.pprint/pprint `(do ~@funcs))))

; see below
(debug units)

(do
 (clojure.core/defn
  to-mm
  [m__32709__auto__]
  (clojure.core/* 1000 m__32709__auto__))
 (clojure.core/defn
  to-m
  [m__32709__auto__]
  (clojure.core/* 1 m__32709__auto__))
 (clojure.core/defn
  to-cm
  [m__32709__auto__]
  (clojure.core/* 100 m__32709__auto__))
 (clojure.core/defn
  to-km
  [m__32709__auto__]
  (clojure.core/* 1/1000 m__32709__auto__)))