"Exception Annotations: Lay of the Land" by Edsko de Vries.
TL;DR: Use ghc 9.12, don’t call throwIO on an argument of type SomeException, and use your own function instead of displayException if you want to see all exception annotations.
https://well-typed.com/blog/2026/05/lay-annotation-land/
#Haskell
Haskell Programming Language
npub1sl…c4lap
2026-05-08 15:23:12 UTC
Author Public Key
npub1slaalhtvnzje5aeshexllflv5qgt8e62pj2k9dkwrzzdssd4mmcq8c4lapSeen on
wss://relay.ditto.pubPublished at
2026-05-08 15:23:12 UTCEvent JSON
{
"id": "194a7b1c7ccc2ebfbd269be1692527253103e253048b13bf61696ce49bb685ce",
"pubkey": "87fbdfdd6c98a59a7730be4dffa7eca010b3e74a0c9562b6ce1884d841b5def0",
"created_at": 1778253792,
"kind": 1,
"tags": [
[
"t",
"haskell"
],
[
"proxy",
"https://fosstodon.org/users/haskell/statuses/116539640530533090",
"activitypub"
],
[
"client",
"Mostr",
"31990:6be38f8c63df7dbf84db7ec4a6e6fbbd8d19dca3b980efad18585c46f04b26f9:mostr",
"wss://relay.ditto.pub"
]
],
"content": "\"Exception Annotations: Lay of the Land\" by Edsko de Vries.\n\n TL;DR: Use ghc 9.12, don’t call throwIO on an argument of type SomeException, and use your own function instead of displayException if you want to see all exception annotations.\n\nhttps://well-typed.com/blog/2026/05/lay-annotation-land/\n\n#Haskell",
"sig": "ad1a34338d7a64a580cce38461f075241f0522f71209139344c690e272f7cde1e7181a7d0ca5724a7ba9d7ee61a86caadfc612b3ab5d4c72589bf8ceb504e799"
}