I had written a post about how to set up reloader.erl about a year ago. Reloader.erl is an incredibly useful library included in mochiweb for automatically reloading erlang libraries if they’ve been recompiled.

I had also written a post about iWatch and phpunit to follow source directories and automatically run a [...]

I wrote this post a few months ago when I was developing a new Erlang application. I eventually ended up using the reloader I mentioned at the end, but never documented it. Now I’m about to start writing a new app, and I’m on a different machine.

First, get the reloader. It [...]

Say you’ve got an Erlang app with the standard file system layout, with your source code in src/ and your compiled code in ebin/. I’ve found this makes using the interactive shell interpreter a little harder.

Lets use the Emakefile that Erlang supports to let us recompile and reload our code on the fly.

[...]

First, make sure you have the compile flag (+debug_info) set when compiling your source, then fire up the debugger:

1> i:im().

My Erlang Makefile:

EBIN_DIR := ebin SRC_DIR := src EXAMPLES_DIR := examples INCLUDE_DIR := include ERLC := erlc ERLC_FLAGS := +debug_info +native -W -I $(INCLUDE_DIR) -o $(EBIN_DIR) all: @mkdir -p $(EBIN_DIR) $(ERLC) $(ERLC_FLAGS) $(SRC_DIR)/*.erl [...]

If you’re running into trouble with Mnesia not writing your data to disk, make sure you create the schema BEFORE you start mnesia. Otherwise you’ll get errors like

opt_disc. Directory “c:/Documents and Settings/jhaddad/workspace/Mnesia.localhost@whatever” is NOT used.

I hate looking stuff up. I just like having this type of thing 1 click away, in a nice summary. This post is mostly for me.

Define a record:

-record( rule, {ruleid, site, rule, original} ).

You can define a record in the shell using rd:

99> rd(rule, {ruleid, site, rule, original} ).
rule

[...]