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data.df_from_csv silently replaces text and empty cells with numeric zero

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
75/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
c
Domain
data-engineering

Research direction

Read lib/data.eigs lines 40–45 and the num contract in docs/SPEC.md, then run the provided CSV reproduction. Add regression coverage in tests/test_data.eigs for text, empty cells, and numeric values, and review docs/STDLIB.md for the inference policy. Done means text and empty cells retain their values and types while valid numbers remain numeric.

Written by the indexing model from the issue text.

Description

area:stdlib bug found-by:code-review kind:silent-wrong

data.df_from_csv silently converts text fields such as names and empty strings into numeric zero. A normal mixed text/numeric CSV loses its names and other textual data on import.

Reproduce

Run from the repository root:

probe_dir=$(mktemp -d)
printf 'name,age,note\nAlice,30,\nBob,0,x12\n' > "$probe_dir/input.csv"
src/eigenscript -e 'import data
argv is args of null
print of (json_encode of (data.df_from_csv of argv[0]))' "$probe_dir/input.csv"

Actual (exit 0):

[{"name":0,"age":30,"note":0},{"name":0,"age":0,"note":0}]

Expected: Alice, Bob, the empty note, and x12 remain strings; 30 and 0 are numeric. This fixture needs no CSV quoting or dialect decisions.

Cause and coverage

lib/data.eigs:40–45 attempts numeric conversion and then checks whether the result has type num. The num contract explicitly converts strings without a leading number to numeric 0, so that check cannot distinguish successful numeric parsing from text. The branch that preserves the original string is unreachable for string cells.

df_from_csv is documented as the typed-column CSV reader. Existing tests/test_data.eigs constructs dataframes with df_from_rows and does not exercise CSV import/export.

A regression should assert both values and types for alphabetic text, empty cells, and valid zero and nonzero numbers. Preserve text rather than using a failed numeric conversion as zero. Decide and document the inference policy for ambiguous numeric-prefix strings such as 12abc; this report does not claim the existing documentation already specifies that case.

Confirmed with a fresh default release build of b91768e23c5a874a64e76e4af9ab291e6aa49983, with inherited EIGS_* variables removed.

Dominant language
C
Stars
3
Forks
7
Avg merge
3h 56m
Merged PRs (30d)
102

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