A company called EROAD built hardware and software for trucks, with most software developed in Java and JavaScript. A two-person mobile team used C# and F# to build Android apps. They wanted to use these languages for a new cross-platform app but were told no by the architect. They secretly used F# in build scripts and a hackathon project, and eventually ported F# code into a production app after the architect left. This led to conversations about using F# and lessons like starting with small F# pieces and waiting for opponents to leave the company.

1. Dr FunctionalLove
or: How EROAD learned to
stop worrying and love F#
Jim Bennett
Senior Cloud Developer Advocate - Microsoft
@jimbobbennett

2. Once upon a time there
was a company in New
Zealand called EROAD…
@jimbobbennett

3. EROAD built hardware for
trucks, and a SaaS
platform that used data
from that hardware
@jimbobbennett

4. EROAD had a 2-person
mobile team
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5. They were the odd ones
out - the rest of the
company built services
and web sites in Java,
HTML and JavaScript
@jimbobbennett

6. But they built Android
apps in C# using Xamarin
@jimbobbennett

7. And they loved F#!
@jimbobbennett

8. One day, they needed to
build a new app on iOS
and Android
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9. They wanted to use
Xamarin.Forms with a C#
UI layer and an F# model
layer
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10. So they went to see
THE ARCHITECT
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11. And guess what he said…
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12. Our two trusty developers
knew his reasons were
not correct…
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13. So they hatched a plan…
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14. Phase #1
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15. The old app used
PowerShell for build
scripts
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16. They needed build scripts
for their new app, so they
used FAKE
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17. They then justified it to the
architect
@jimbobbennett

18. That meant F# was in
production…
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19. Phase #2
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20. EROAD Hackathon!
24 hours to build
something, no rules on
tech…
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21. They used
Xamarin.Forms with a C#
UI layer and an F# model
layer
@jimbobbennett

22. It was an almost
production ready app in
24 hours
@jimbobbennett

23. If they released it - F#
would be in a production
app!
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24. Bonus Phase…
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25. The architect left!
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26. Phase #3
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27. They ported their F#
model code to their
production app
@jimbobbennett

28. They justified it to their
boss…
@jimbobbennett

29. They justified it to their
boss…
@jimbobbennett

30. They justified it to their
boss…
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31. Who said…
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32. Yes!
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33. They had F# inside an
app on the iOS App Store
and Google Play Store
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34. This inspired
conversations
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35. They learnt things…
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36. There are different ways
to use F#
@jimbobbennett

37. Once it is in production it’s
easier to justify using it
again
@jimbobbennett

38. Use it for small pieces first
- easy to replace if it goes
wrong
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39. Work for a company that
values their developers
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40. Wait for the naysayers to
leave!
@jimbobbennett

41. If all else fails – do it
anyway then ask for
forgiveness!
@jimbobbennett

42. No architects were harmed in the making of these slides. The old head of architecture at EROAD is NOT evil, is a really nice chap and was totally
justified in his hesitation to adopt an unknown technology. We love you Jordan!
Jim Bennett
Senior Cloud Developer Advocate -
Microsoft
@jimbobbennett
jimbobbennett.io
Sam Williams
Development team lead - EROAD
@willsam100
codingwithsam.com