IndexedStateT has superfluous parts
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Description
Digging into the definition of IndexedStateT we find
F[(SA) ⇒ F[(SB, A)]]
but that outer F isn't motivated by anything in the underlying theory.
(SA) ⇒ F[(SB, A)]
is actual indexed state. The extra outer F[_] seems to have slipped in as a sort of Cayley-like construction, but it goes conspicuously unused, and if you attempt to use it to say slip another layer of F effects in during the glue-up of your computation, you'll violate laws left and right for non-commutative choices of F[_]. The inner F is motivated by the fact that you can distribute the (SA) => out of any F[] using strength, and (SB,) in using strength.
Is there any documentation motivating/justifying this extra outer effect layer?
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the IndexedStateT definition and the theoretical reasoning described in the issue. Determine whether existing documentation justifies the outer F layer or whether the issue calls for a design decision; done means the motivation and intended direction are clearly documented.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- scala
- Domain
- developer-experience
- Issue type
- Documentation
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100