<div class="protonmail_signature_block">Hello,<br></div><div class="protonmail_signature_block"><br></div><div class="protonmail_signature_block">I wrote some code for a parking meter to understand how gen_fsm works. There are two states (awaiting_payment, valid_ticket), two input messages (payment, cancel_ticket), and three output messages (unpaid, change, refund).<br></div><div class="protonmail_signature_block"><br></div><div class="protonmail_signature_block">I'm getting the following error and don't understand what's wrong. Any pointers?<br></div><div class="protonmail_signature_block"><br></div><div class="protonmail_signature_block"><b>Error:</b><br></div><div>** exception exit: {{function_clause,[{gen,do_for_proc,<br></div><div>                                           [{ok,<0.40.0>},#Fun<gen.0.132519590>],<br></div><div>                                           [{file,"gen.erl"},{line,252}]},<br></div><div>                                      {gen_fsm,sync_send_event,2,<br></div><div>                                               [{file,"gen_fsm.erl"},{line,219}]},<br></div><div>                                      {ticketing_fsm,demo1,0,<br></div><div>                                                     [{file,"ticketing_fsm.erl"},{line,25}]},<br></div><div>                                      {erl_eval,do_apply,6,[{file,"erl_eval.erl"},{line,674}]},<br></div><div>                                      {shell,exprs,7,[{file,"shell.erl"},{line,686}]},<br></div><div>                                      {shell,eval_exprs,7,[{file,"shell.erl"},{line,641}]},<br></div><div>                                      {shell,eval_loop,3,[{file,"shell.erl"},{line,626}]}]},<br></div><div>                    {gen_fsm,sync_send_event,[{ok,<0.40.0>},{payment,100}]}}<br></div><div>     in function  gen_fsm:sync_send_event/2 (gen_fsm.erl, line 223)<br></div><div>     in call from ticketing_fsm:demo1/0 (ticketing_fsm.erl, line 25)<br></div><div class="protonmail_signature_block"><br></div><div class="protonmail_signature_block"><b>Source</b>: <a href="https://transfer.sh/M7n3b/ticketing-fsm.erl">https://transfer.sh/M7n3b/ticketing-fsm.erl</a><br></div><div class="protonmail_signature_block"><br></div><div class="protonmail_signature_block">Tobias<br></div>