Improve error message on wrong indentation of let expression inside do block
Given this code:
action NewEventAction = do
now <- getCurrentTime
let event = newRecord @Event
|> set #createdAt now -- THIS LINE NEEDS MORE INDENTATION
render NewView { .. }GHC errors with:
Admin/Controller/Events.hs:26:9: error:
The last statement in a 'do' block must be an expression
let event = newRecord @Event
|
26 | let event = newRecord @Event
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^...A better error message would be:
Admin/Controller/Events.hs:26:9: error:
The let-expression is only indented 4 spaces from the do-statement, but it needs to be indented 8 spaces
'|> set #createdAt now'
|
26 | let event = newRecord @Event
27 | |> set #createdAt now
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^...This issue has happend during a twitch livestream of someone building an IHP app for the first time. Here's a link to the video of that livestream: https://youtu.be/Bncy8JiHDYU?t=4939 At 1:22:19 the user get's stuck. It's kind of interesting to watch as you can see how the error message is a bad UX for someone new to haskell :) Hope we can improve this.