Fun experiment

crazy_fun.erl

-module(crazy_fun).

-export([science/0]).

science() ->
    fun () ->
            'nothing_to_see_here'
    end.

crazy_fun_new.erl

-module(crazy_fun).

-export([science/0]).

science() ->
    fun () ->
            'something_to_see_here?'
    end.

version() ->
    three.

transcript

Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.5  (abort with ^G)
1> c(crazy_fun).
{ok,crazy_fun}
2> crazy_fun:
module_info/0  module_info/1  science/0      
2> F = crazy_fun:science().
#Fun<crazy_fun.0.71331273>
3> file:write_file("dynamite.erlfun", erlang:term_to_binary(crazy_fun:science())).
ok
4> code:delete(crazy_fun).
true
5> code:purge(crazy_fun).
*** ERROR: Shell process terminated! ***
Eshell V5.8.5  (abort with ^G)
1> 
User switch command
 --> q

%% crazy_fun module no-longer in code path:

nem@dhcp-164 ~ % erl
Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.5  (abort with ^G)
1> F = binary_to_term(element(2, file:read_file("tmp/dynamite.erlfun"))).
#Fun<crazy_fun.0.71331273>
2> f().
ok
3> F = binary_to_term(element(2, file:read_file("tmp/dynamite.erlfun"))).
#Fun<crazy_fun.0.71331273>
4> F().
** exception error: {undef,[{#Fun<crazy_fun.0.71331273>,[]},
                            {erl_eval,do_apply,5},
                            {shell,exprs,7},
                            {shell,eval_exprs,7},
                            {shell,eval_loop,3}]}
5> 
User switch command
 --> q

%% new version, unchanged fun body
nem@dhcp-164 ~/tmp % erl   
Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.5  (abort with ^G)
1> c(crazy_fun). 
./crazy_fun.erl:10: Warning: function version/0 is unused
{ok,crazy_fun}
2> F = binary_to_term(element(2, file:read_file("tmp/dynamite.erlfun"))).
** exception error: bad argument
     in function  binary_to_term/1
        called as binary_to_term(enoent)
3> F = binary_to_term(element(2, file:read_file("dynamite.erlfun"))).    
#Fun<crazy_fun.0.71331273>
4> F().
nothing_to_see_here
5> 
User switch command
 --> q

%% updated fun body
nem@dhcp-164 ~/tmp % erl
Erlang R14B04 (erts-5.8.5) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.5  (abort with ^G)
1> c(crazy_fun, [load]).
./crazy_fun.erl:10: Warning: function version/0 is unused
{ok,crazy_fun}
2> F = binary_to_term(element(2, file:read_file("dynamite.erlfun"))).
#Fun<crazy_fun.0.71331273>
3> F().
** exception error: bad function #Fun<crazy_fun.0.71331273>
4> 
User switch command
 --> q