ngless-toolkit / ngless-toolkit/ngless

Implement readset return type types for modules

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enhancement
Dominant language
Rust
Stars
152
Forks
23
PR merge metrics
No merged PRs in 30d

Description

We were trying to add a filtering step as an external module (having a read set as input and output). However, only counts and mapped read sets are supported at the moment, everything else throws an exception:

https://github.com/ngless-toolkit/ngless/blob/bd2bed1f5d951f757c82bf4853c66103f91b5b14/NGLess/ExternalModules.hs#L284

We circumvented this by loading the results with load_mocat_sample, so we don't have an urgent need to have this added to the source code. But perhaps a note in the documentation on the rtype would be helpful.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at NGLess/ExternalModules.hs around line 284, where unsupported external-module return types are rejected. Read the surrounding rtype handling and the documentation for rtype. Done means readset inputs and outputs are supported as intended, or the documentation clearly records the remaining limitation and workaround.

Written by the indexing model from the issue text.

Assessment

Tech stack
haskell
Domain
tooling
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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