The document discusses using the ATS functional programming language to develop safer IoT applications for the ESP8266 WiFi module. ATS supports dependent types, linear types, and optional memory management features that could help prevent common issues like memory safety bugs. The document outlines a demo project implementing JSON output on the ESP8266 using ATS and points out how the type system helps catch errors related to freeing memory correctly. It also advertises an upcoming meetup to discuss functional IoT development further.

1. Safer IoT using functional languageSafer IoT using functional languageSafer IoT using functional languageSafer IoT using functional languageSafer IoT using functional language
Kiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICS

2. Hardware: ESP8266Hardware: ESP8266Hardware: ESP8266Hardware: ESP8266Hardware: ESP8266
☆ http://espressif.com/en/products/wroom/☆ http://espressif.com/en/products/wroom/☆ http://espressif.com/en/products/wroom/☆ http://espressif.com/en/products/wroom/☆ http://espressif.com/en/products/wroom/
☆ 32-bit low power MCU Wi-Fi Module☆ 32-bit low power MCU Wi-Fi Module☆ 32-bit low power MCU Wi-Fi Module☆ 32-bit low power MCU Wi-Fi Module☆ 32-bit low power MCU Wi-Fi Module
☆ Having integrated TCP/IP network stacks☆ Having integrated TCP/IP network stacks☆ Having integrated TCP/IP network stacks☆ Having integrated TCP/IP network stacks☆ Having integrated TCP/IP network stacks
☆ Including ADC, SDIO, UART, PWM, I2C ...☆ Including ADC, SDIO, UART, PWM, I2C ...☆ Including ADC, SDIO, UART, PWM, I2C ...☆ Including ADC, SDIO, UART, PWM, I2C ...☆ Including ADC, SDIO, UART, PWM, I2C ...
☆ Small form factor of only 18mm x 20mm☆ Small form factor of only 18mm x 20mm☆ Small form factor of only 18mm x 20mm☆ Small form factor of only 18mm x 20mm☆ Small form factor of only 18mm x 20mm

3. Functional language: ATSFunctional language: ATSFunctional language: ATSFunctional language: ATSFunctional language: ATS
☆ http://www.ats-lang.org/☆ http://www.ats-lang.org/☆ http://www.ats-lang.org/☆ http://www.ats-lang.org/☆ http://www.ats-lang.org/
☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML
☆ DML-style dependent types☆ DML-style dependent types☆ DML-style dependent types☆ DML-style dependent types☆ DML-style dependent types
☆ Linear types☆ Linear types☆ Linear types☆ Linear types☆ Linear types
☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC
☆ Optional malloc/free☆ Optional malloc/free☆ Optional malloc/free☆ Optional malloc/free☆ Optional malloc/free
☆ Optional run-time☆ Optional run-time☆ Optional run-time☆ Optional run-time☆ Optional run-time

4. DemoDemoDemoDemoDemo
The code is found at following:The code is found at following:The code is found at following:The code is found at following:The code is found at following:
https://github.com/fpiot/esp8266-atshttps://github.com/fpiot/esp8266-atshttps://github.com/fpiot/esp8266-atshttps://github.com/fpiot/esp8266-atshttps://github.com/fpiot/esp8266-ats

5. Demo environmentDemo environmentDemo environmentDemo environmentDemo environment

6. Software architectureSoftware architectureSoftware architectureSoftware architectureSoftware architecture

7. ATS finds forgetting free memoryATS finds forgetting free memoryATS finds forgetting free memoryATS finds forgetting free memoryATS finds forgetting free memory
$�cd�esp8266-ats/ifttt_ats
$�vi�user/user_main.dats
�39�����val�json_open�=�string0_copy�"{"value1":�""
�40�����val�json_close�=�string0_copy�""�}"
�41�����val�temp�=�esp_tostrptr_int�rand
�42�����val�json_head�=�strptr_append�(json_open,�temp)
�43�����val�json_data�=�strptr_append�(json_head,�json_close)
�44�//��val�()�=�(free�json_open;�free�json_close;�free�temp;�free�json_head)
�45�����val�()�=�(free�json_open;�free�json_close;�free�temp)�//�Error!
$�make
ATS�user/user_main.dats
/home/kiwamu/src/esp8266-ats/ifttt_ats/user/user_main.dats:�985(line=32,�
offs=43)�--�2237(line=55,�offs=4):�error(3):�the�linear�dynamic�variable�
[json_head$3823(-1)]�needs�to�be�consumed�but�it�is�preserved�with�the�type�
[S2Eapp(S2Ecst(strptr_addr_vtype);�S2EVar(4441))]�instead.
$�cd�esp8266-ats/ifttt_ats
$�vi�user/user_main.dats
�39�����val�json_open�=�string0_copy�"{"value1":�""
�40�����val�json_close�=�string0_copy�""�}"
�41�����val�temp�=�esp_tostrptr_int�rand
�42�����val�json_head�=�strptr_append�(json_open,�temp)
�43�����val�json_data�=�strptr_append�(json_head,�json_close)
�44�//��val�()�=�(free�json_open;�free�json_close;�free�temp;�free�json_head)
�45�����val�()�=�(free�json_open;�free�json_close;�free�temp)�//�Error!
$�make
ATS�user/user_main.dats
/home/kiwamu/src/esp8266-ats/ifttt_ats/user/user_main.dats:�985(line=32,�
offs=43)�--�2237(line=55,�offs=4):�error(3):�the�linear�dynamic�variable�
[json_head$3823(-1)]�needs�to�be�consumed�but�it�is�preserved�with�the�type�
[S2Eapp(S2Ecst(strptr_addr_vtype);�S2EVar(4441))]�instead.
$�cd�esp8266-ats/ifttt_ats
$�vi�user/user_main.dats
�39�����val�json_open�=�string0_copy�"{"value1":�""
�40�����val�json_close�=�string0_copy�""�}"
�41�����val�temp�=�esp_tostrptr_int�rand
�42�����val�json_head�=�strptr_append�(json_open,�temp)
�43�����val�json_data�=�strptr_append�(json_head,�json_close)
�44�//��val�()�=�(free�json_open;�free�json_close;�free�temp;�free�json_head)
�45�����val�()�=�(free�json_open;�free�json_close;�free�temp)�//�Error!
$�make
ATS�user/user_main.dats
/home/kiwamu/src/esp8266-ats/ifttt_ats/user/user_main.dats:�985(line=32,�
offs=43)�--�2237(line=55,�offs=4):�error(3):�the�linear�dynamic�variable�
[json_head$3823(-1)]�needs�to�be�consumed�but�it�is�preserved�with�the�type�
[S2Eapp(S2Ecst(strptr_addr_vtype);�S2EVar(4441))]�instead.
$�cd�esp8266-ats/ifttt_ats
$�vi�user/user_main.dats
�39�����val�json_open�=�string0_copy�"{"value1":�""
�40�����val�json_close�=�string0_copy�""�}"
�41�����val�temp�=�esp_tostrptr_int�rand
�42�����val�json_head�=�strptr_append�(json_open,�temp)
�43�����val�json_data�=�strptr_append�(json_head,�json_close)
�44�//��val�()�=�(free�json_open;�free�json_close;�free�temp;�free�json_head)
�45�����val�()�=�(free�json_open;�free�json_close;�free�temp)�//�Error!
$�make
ATS�user/user_main.dats
/home/kiwamu/src/esp8266-ats/ifttt_ats/user/user_main.dats:�985(line=32,�
offs=43)�--�2237(line=55,�offs=4):�error(3):�the�linear�dynamic�variable�
[json_head$3823(-1)]�needs�to�be�consumed�but�it�is�preserved�with�the�type�
[S2Eapp(S2Ecst(strptr_addr_vtype);�S2EVar(4441))]�instead.
$�cd�esp8266-ats/ifttt_ats
$�vi�user/user_main.dats
�39�����val�json_open�=�string0_copy�"{"value1":�""
�40�����val�json_close�=�string0_copy�""�}"
�41�����val�temp�=�esp_tostrptr_int�rand
�42�����val�json_head�=�strptr_append�(json_open,�temp)
�43�����val�json_data�=�strptr_append�(json_head,�json_close)
�44�//��val�()�=�(free�json_open;�free�json_close;�free�temp;�free�json_head)
�45�����val�()�=�(free�json_open;�free�json_close;�free�temp)�//�Error!
$�make
ATS�user/user_main.dats
/home/kiwamu/src/esp8266-ats/ifttt_ats/user/user_main.dats:�985(line=32,�
offs=43)�--�2237(line=55,�offs=4):�error(3):�the�linear�dynamic�variable�
[json_head$3823(-1)]�needs�to�be�consumed�but�it�is�preserved�with�the�type�
[S2Eapp(S2Ecst(strptr_addr_vtype);�S2EVar(4441))]�instead.

8. Functional IoT Meetup at January 30Functional IoT Meetup at January 30Functional IoT Meetup at January 30Functional IoT Meetup at January 30Functional IoT Meetup at January 30

9. License of photosLicense of photosLicense of photosLicense of photosLicense of photos
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*�JTAG�board�1�￨�Flickr�-�Photo�Sharing!
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��https://www.flickr.com/photos/steren/2732488224/
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