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ts-02-groupby

0.000
0/1 tests· typing

Proposed solution

```ts
export function groupBy<T, K extends string | number>(
  items: T[],
  keyFn: (item: T) => K,
): Record<K, T[]>
```

Test output (stdout)

TAP version 13
# /tmp/llmlab-ts-02-groupby-1tl7hzmh/solution.test.ts:3
# import { groupBy } from "./solution.ts";
#          ^
# SyntaxError: The requested module './solution.ts' does not provide an export named 'groupBy'
#     at \#asyncInstantiate (node:internal/modules/esm/module_job:327:21)
#     at async ModuleJob.run (node:internal/modules/esm/module_job:431:5)
#     at async node:internal/modules/esm/loader:633:26
#     at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:101:5)
# Node.js v24.16.0
# Subtest: solution.test.ts
not ok 1 - solution.test.ts
  ---
  duration_ms: 63.457695
  type: 'test'
  location: '/tmp/llmlab-ts-02-groupby-1tl7hzmh/solution.test.ts:1:1'
  failureType: 'testCodeFailure'
  exitCode: 1
  signal: ~
  error: 'test failed'
  code: 'ERR_TEST_FAILURE'
  ...
1..1
# tests 1
# suites 0
# pass 0
# fail 1
# cancelled 0
# skipped 0
# todo 0
# duration_ms 67.366756
Self-repair attempts
[
  {
    "total": 1,
    "answer": "```ts\nexport function groupBy<T, K extends string | number>(\n  items: T[],\n  keyFn: (item: T) => K,\n): Record<K, T[]>\n```",
    "passed": 0,
    "test_error": "TAP version 13\n# /tmp/llmlab-ts-02-groupby-1tl7hzmh/solution.test.ts:3\n# import { groupBy } from \"./solution.ts\";\n#          ^\n# SyntaxError: The requested module './solution.ts' does not provide an export named 'groupBy'\n#     at \\#asyncInstantiate (node:internal/modules/esm/module_job:327:21)\n#     at async ModuleJob.run (node:internal/modules/esm/module_job:431:5)\n#     at async node:internal/modules/esm/loader:633:26\n#     at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:101:5)\n# Node.js v24.16.0\n# Subtest: solution.test.ts\nnot ok 1 - solution.test.ts\n  ---\n  duration_ms: 63.457695\n  type: 'test'\n  location: '/tmp/llmlab-ts-02-groupby-1tl7hzmh/solution.test.ts:1:1'\n  failureType: 'testCodeFailure'\n  exitCode: 1\n  signal: ~\n  error: 'test failed'\n  code: 'ERR_TEST_FAILURE'\n  ...\n1..1\n# tests 1\n# suites 0\n# pass 0\n# fail 1\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 67.366756"
  },
  {
    "total": 6,
    "answer": "```ts\nexport function groupBy<T, K extends string | number>(\n  items: T[],\n  keyFn: (item: T) => K,\n): Record<K, T[]> {\n  return items.reduce((acc, item) => {\n    const key = keyFn(item);\n    if (!acc[key]) {\n      acc[key] = [];\n    }\n    acc[key].push(item);\n    return acc;\n  }, {} as Record<K, T[]>);\n}\n```",
    "passed": 6,
    "test_error": ""
  }
]
System prompt
You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.