You might also want to check out Chronicle monad in these package:
https://hackage.haskell.org/package/these-0.6.2.1/docs/Control-Monad-Chronic...
Kind regards,
Nick
On Sat, 6 Feb 2016 at 11:58, Roman Cheplyaka
It sounds like you want the Validation applicative functor. See e.g. https://ro-che.info/articles/2015-05-02-smarter-validation
On 02/06/2016 04:58 AM, Lian Hung Hon wrote:
Dear haskellers,
I have a multi-step computation. The steps are predefined, but users can choose which steps to execute (something like a recipe). Here is an example recipe:
Step 1 - Get data from network (multiple HTTP calls) and put into a list Step 2 - Process the data (e.g. average, sum, median, etc.) Step 3 - Persist result to database
Sometimes, Step 1 can fail for some of the HTTP calls. When this happens, Step 2 should continue as much as possible using whatever data that has been retrieved, but somehow indicate that an error has occurred and the result is partial.
Q1: What is the idiomatic way of achieving this? Using throwError in Control.Monad.Except aborts the computation, which isn't what I want.
Q2: (General software design) Furthermore, where should the error be logged? Logging it in both Step 1 and 2 preserves modularity for each of the steps, unfortunately it would result in duplicate error messages. What is the best practice for this?
Regards, Hon
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