Added support for LFE (Lisp Flavored Erlang).

samples/LFE/mnesia_demo.lfe

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+;; Copyright (c) 2008-2013 Robert Virding
+;;
+;; Licensed under the Apache License, Version 2.0 (the "License");
+;; you may not use this file except in compliance with the License.
+;; You may obtain a copy of the License at
+;;
+;;     http://www.apache.org/licenses/LICENSE-2.0
+;;
+;; Unless required by applicable law or agreed to in writing, software
+;; distributed under the License is distributed on an "AS IS" BASIS,
+;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;; See the License for the specific language governing permissions and
+;; limitations under the License.
+
+;; File    : mnesia_demo.lfe
+;; Author  : Robert Virding
+;; Purpose : A simple Mnesia demo file for LFE.
+
+;; This file contains a simple demo of using LFE to access Mnesia
+;; tables.  It shows how to use the emp-XXXX macro (ETS match pattern)
+;; together with mnesia:match_object, match specifications with
+;; mnesia:select and Query List Comprehensions.
+
+(defmodule mnesia_demo
+  (export (new 0) (by_place 1) (by_place_ms 1) (by_place_qlc 1)))
+
+(defrecord person name place job)
+
+(defun new ()
+  ;; Start mnesia and create a table, we will get an in memory only schema.
+  (: mnesia start)
+  (: mnesia create_table 'person '(#(attributes (name place job))))
+  ;; Initialise the table.
+  (let ((people '(
+          ;; First some people in London.
+          #(fred london waiter)
+          #(bert london waiter)
+          #(john london painter)
+          #(paul london driver)
+          ;; Now some in Paris.
+          #(jean paris waiter)
+          #(gerard paris driver)
+          #(claude paris painter)
+          #(yves paris waiter)
+          ;; And some in Rome.
+          #(roberto rome waiter)
+          #(guiseppe rome driver)
+          #(paulo rome painter)
+          ;; And some in Berlin.
+          #(fritz berlin painter)
+          #(kurt berlin driver)
+          #(hans berlin waiter)
+          #(franz berlin waiter)
+          )))
+    (: lists foreach (match-lambda
+               ([(tuple n p j)]
+            (: mnesia transaction
+              (lambda ()
+                (let ((new (make-person name n place p job j)))
+                  (: mnesia write new))))))
+       people)))
+
+;; Match records by place using match_object and the emp-XXXX macro.
+(defun by_place (place)
+  (: mnesia transaction
+    (lambda () (: mnesia match_object (emp-person place place)))))
+
+;; Use match specifications to match records
+(defun by_place_ms (place)
+  (let ((f (lambda () (: mnesia select 'person
+             (match-spec ([(match-person name n place p job j)]
+                      (when (=:= p place))
+                      (tuple n j)))))))
+    (: mnesia transaction f)))
+
+;; Use Query List Comprehensions to match records
+(defun by_place_qlc (place)
+  (let ((f (lambda ()
+         (let ((q (qlc (lc ((<- person (: mnesia table 'person))
+                (=:= (person-place person) place))
+                 person))))
+           (: qlc e q)))))
+    (: mnesia transaction f)))