Find typeclass instances #22

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opened 2026-01-05 21:16:35 +00:00 by mprihoda · 0 comments

mprihoda commented

2026-01-05 21:16:35 +00:00

(Migrated from github.com)

Problem

Agent needs to know where to find typeclass instances:

"Where is the Monad[IO] instance defined?"
"Which library provides Encoder[LocalDateTime]?"
"What instances are available for Show?"

Proposed Solution

New Tool: `find_typeclass_instances`

{
  "name": "find_typeclass_instances",
  "description": "Find typeclass instances for a type",
  "input": {
    "coordinates": "Maven/Coursier coordinates",
    "typeclass": "Typeclass name (e.g., Monad, Encoder)",
    "forType": "optional, type to find instance for",
    "scalaVersion": "optional"
  }
}

Example 1: Find instances of a typeclass

find_typeclass_instances("org.typelevel::cats-core:2.10.0", "Monad")

Returns:

{
  "typeclass": "cats.Monad",
  "instances": [
    {"forType": "Option", "location": "cats.instances.option._", "import": "import cats.implicits._"},
    {"forType": "List", "location": "cats.instances.list._", "import": "import cats.implicits._"},
    {"forType": "Either[E, *]", "location": "cats.instances.either._", "import": "import cats.implicits._"}
  ]
}

Example 2: Find instances for a specific type

find_typeclass_instances("io.circe::circe-core:0.14.6", "Encoder", forType="java.time.LocalDate")

Returns:

{
  "typeclass": "io.circe.Encoder",
  "forType": "java.time.LocalDate",
  "instances": [
    {
      "location": "io.circe.java8.time._",
      "import": "import io.circe.java8.time._",
      "artifact": "io.circe::circe-java8:0.14.6",
      "note": "Requires additional dependency"
    }
  ]
}

Implementation

Parse companion objects for given/implicit definitions
Scan package objects for instances
Use TASTy for accurate type information
Build index of typeclass → instances

Value for Agent

Knows where to get missing instances
Discovers required imports
Finds instances in separate artifacts

Acceptance Criteria

Find instances defined in companion objects
Find instances in package objects
Include required import statement
Note if instance requires additional dependency

## Problem Agent needs to know where to find typeclass instances: - "Where is the `Monad[IO]` instance defined?" - "Which library provides `Encoder[LocalDateTime]`?" - "What instances are available for `Show`?" ## Proposed Solution ### New Tool: `find_typeclass_instances` ```json { "name": "find_typeclass_instances", "description": "Find typeclass instances for a type", "input": { "coordinates": "Maven/Coursier coordinates", "typeclass": "Typeclass name (e.g., Monad, Encoder)", "forType": "optional, type to find instance for", "scalaVersion": "optional" } } ``` **Example 1: Find instances of a typeclass** ``` find_typeclass_instances("org.typelevel::cats-core:2.10.0", "Monad") ``` **Returns:** ```json { "typeclass": "cats.Monad", "instances": [ {"forType": "Option", "location": "cats.instances.option._", "import": "import cats.implicits._"}, {"forType": "List", "location": "cats.instances.list._", "import": "import cats.implicits._"}, {"forType": "Either[E, *]", "location": "cats.instances.either._", "import": "import cats.implicits._"} ] } ``` **Example 2: Find instances for a specific type** ``` find_typeclass_instances("io.circe::circe-core:0.14.6", "Encoder", forType="java.time.LocalDate") ``` **Returns:** ```json { "typeclass": "io.circe.Encoder", "forType": "java.time.LocalDate", "instances": [ { "location": "io.circe.java8.time._", "import": "import io.circe.java8.time._", "artifact": "io.circe::circe-java8:0.14.6", "note": "Requires additional dependency" } ] } ``` ## Implementation - Parse companion objects for `given`/`implicit` definitions - Scan package objects for instances - Use TASTy for accurate type information - Build index of typeclass → instances ## Value for Agent - Knows where to get missing instances - Discovers required imports - Finds instances in separate artifacts ## Acceptance Criteria - [ ] Find instances defined in companion objects - [ ] Find instances in package objects - [ ] Include required import statement - [ ] Note if instance requires additional dependency