Understand the failure.
Verify the repair.
Small, reproducible software failures. The broken implementation, the fix that didn’t work, and the one that passed—preserved together.
Explore the cases ↓How results are verified ↗WHAT THE ARCHIVE CONTAINS
100840 executable cases. 20168 are open.
Every case records the implementation that fails, the fix that did not work, and the repair that passed its checks—with recorded outputs and source hashes. This release adds 100840 cases across 20168 failure mechanisms and 254 domains.
The open tier gives you the failure and the unsuccessful fix for one case in every mechanism. The remaining 80672 cases, 5 variants per mechanism, are member-only: the verified repair, its recorded checks, and the full fixture suite are held in the member archive. Read the methodology ↗
A RECORD OF WHAT WENT WRONG
Browse the archive / 100840
Stable value ranking · case 01
The operation returns a result or retained state that violates this contract: Sort values lexically and retain original positions, preserving original order among equal values.
Stable value ranking · case 02
The operation returns a result or retained state that violates this contract: Sort values lexically and retain original positions, preserving original order among equal values.
Stable value ranking · case 03
The operation returns a result or retained state that violates this contract: Sort values lexically and retain original positions, preserving original order among equal values.
Stable value ranking · case 04
The operation returns a result or retained state that violates this contract: Sort values lexically and retain original positions, preserving original order among equal values.
Stable value ranking · case 05
The operation returns a result or retained state that violates this contract: Sort values lexically and retain original positions, preserving original order among equal values.
Adjacent change positions · case 01
The operation returns a result or retained state that violates this contract: Return indices whose element differs from its predecessor; position zero is not a change.
Adjacent change positions · case 02
The operation returns a result or retained state that violates this contract: Return indices whose element differs from its predecessor; position zero is not a change.
Adjacent change positions · case 03
The operation returns a result or retained state that violates this contract: Return indices whose element differs from its predecessor; position zero is not a change.
Adjacent change positions · case 04
The operation returns a result or retained state that violates this contract: Return indices whose element differs from its predecessor; position zero is not a change.
Adjacent change positions · case 05
The operation returns a result or retained state that violates this contract: Return indices whose element differs from its predecessor; position zero is not a change.
First occurrence positions · case 01
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value first appears.
First occurrence positions · case 02
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value first appears.
First occurrence positions · case 03
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value first appears.
First occurrence positions · case 04
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value first appears.
First occurrence positions · case 05
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value first appears.
Last occurrence positions · case 01
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value last appears, ordered by position.
Last occurrence positions · case 02
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value last appears, ordered by position.
Last occurrence positions · case 03
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value last appears, ordered by position.
Last occurrence positions · case 04
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value last appears, ordered by position.
Last occurrence positions · case 05
The operation returns a result or retained state that violates this contract: Return positions at which each distinct value last appears, ordered by position.
Occurrence count per position · case 01
The operation returns a result or retained state that violates this contract: Return the full-list occurrence count corresponding to each original element.
Occurrence count per position · case 02
The operation returns a result or retained state that violates this contract: Return the full-list occurrence count corresponding to each original element.
Occurrence count per position · case 03
The operation returns a result or retained state that violates this contract: Return the full-list occurrence count corresponding to each original element.
Occurrence count per position · case 04
The operation returns a result or retained state that violates this contract: Return the full-list occurrence count corresponding to each original element.
Occurrence count per position · case 05
The operation returns a result or retained state that violates this contract: Return the full-list occurrence count corresponding to each original element.
Occurrence ordinal per position · case 01
The operation returns a result or retained state that violates this contract: Return each occurrence ordinal within its equal-value subsequence, starting at one.
Occurrence ordinal per position · case 02
The operation returns a result or retained state that violates this contract: Return each occurrence ordinal within its equal-value subsequence, starting at one.
Occurrence ordinal per position · case 03
The operation returns a result or retained state that violates this contract: Return each occurrence ordinal within its equal-value subsequence, starting at one.
Occurrence ordinal per position · case 04
The operation returns a result or retained state that violates this contract: Return each occurrence ordinal within its equal-value subsequence, starting at one.
Occurrence ordinal per position · case 05
The operation returns a result or retained state that violates this contract: Return each occurrence ordinal within its equal-value subsequence, starting at one.
Concatenation order and duplicates · case 01
The operation returns a result or retained state that violates this contract: Concatenate left then right, retaining every occurrence.
Concatenation order and duplicates · case 02
The operation returns a result or retained state that violates this contract: Concatenate left then right, retaining every occurrence.
Concatenation order and duplicates · case 03
The operation returns a result or retained state that violates this contract: Concatenate left then right, retaining every occurrence.
Concatenation order and duplicates · case 04
The operation returns a result or retained state that violates this contract: Concatenate left then right, retaining every occurrence.
Concatenation order and duplicates · case 05
The operation returns a result or retained state that violates this contract: Concatenate left then right, retaining every occurrence.
Stable set union · case 01
The operation returns a result or retained state that violates this contract: Return unique union values in first appearance order across left then right.
Stable set union · case 02
The operation returns a result or retained state that violates this contract: Return unique union values in first appearance order across left then right.
Stable set union · case 03
The operation returns a result or retained state that violates this contract: Return unique union values in first appearance order across left then right.
Stable set union · case 04
The operation returns a result or retained state that violates this contract: Return unique union values in first appearance order across left then right.
Stable set union · case 05
The operation returns a result or retained state that violates this contract: Return unique union values in first appearance order across left then right.
Stable set intersection · case 01
The operation returns a result or retained state that violates this contract: Return unique left values also present in right, preserving left first-appearance order.
Stable set intersection · case 02
The operation returns a result or retained state that violates this contract: Return unique left values also present in right, preserving left first-appearance order.
Stable set intersection · case 03
The operation returns a result or retained state that violates this contract: Return unique left values also present in right, preserving left first-appearance order.
Stable set intersection · case 04
The operation returns a result or retained state that violates this contract: Return unique left values also present in right, preserving left first-appearance order.
Stable set intersection · case 05
The operation returns a result or retained state that violates this contract: Return unique left values also present in right, preserving left first-appearance order.
Left semijoin preserves left duplicates · case 01
The operation returns a result or retained state that violates this contract: Retain every left occurrence whose value occurs anywhere in right.
Left semijoin preserves left duplicates · case 02
The operation returns a result or retained state that violates this contract: Retain every left occurrence whose value occurs anywhere in right.
Left semijoin preserves left duplicates · case 03
The operation returns a result or retained state that violates this contract: Retain every left occurrence whose value occurs anywhere in right.
Left semijoin preserves left duplicates · case 04
The operation returns a result or retained state that violates this contract: Retain every left occurrence whose value occurs anywhere in right.
Left semijoin preserves left duplicates · case 05
The operation returns a result or retained state that violates this contract: Retain every left occurrence whose value occurs anywhere in right.
Stable set difference · case 01
The operation returns a result or retained state that violates this contract: Return distinct left values absent from right, preserving first appearance order.
Stable set difference · case 02
The operation returns a result or retained state that violates this contract: Return distinct left values absent from right, preserving first appearance order.
Stable set difference · case 03
The operation returns a result or retained state that violates this contract: Return distinct left values absent from right, preserving first appearance order.
Stable set difference · case 04
The operation returns a result or retained state that violates this contract: Return distinct left values absent from right, preserving first appearance order.
Stable set difference · case 05
The operation returns a result or retained state that violates this contract: Return distinct left values absent from right, preserving first appearance order.
Left filter difference keeps occurrences · case 01
The operation returns a result or retained state that violates this contract: Retain all left occurrences with no equal value in right.
Left filter difference keeps occurrences · case 02
The operation returns a result or retained state that violates this contract: Retain all left occurrences with no equal value in right.
Left filter difference keeps occurrences · case 03
The operation returns a result or retained state that violates this contract: Retain all left occurrences with no equal value in right.
Left filter difference keeps occurrences · case 04
The operation returns a result or retained state that violates this contract: Retain all left occurrences with no equal value in right.
Left filter difference keeps occurrences · case 05
The operation returns a result or retained state that violates this contract: Retain all left occurrences with no equal value in right.
Stable symmetric set difference · case 01
The operation returns a result or retained state that violates this contract: Return left-only then right-only unique values in their respective first-appearance orders.
Stable symmetric set difference · case 02
The operation returns a result or retained state that violates this contract: Return left-only then right-only unique values in their respective first-appearance orders.
Stable symmetric set difference · case 03
The operation returns a result or retained state that violates this contract: Return left-only then right-only unique values in their respective first-appearance orders.
Stable symmetric set difference · case 04
The operation returns a result or retained state that violates this contract: Return left-only then right-only unique values in their respective first-appearance orders.
Stable symmetric set difference · case 05
The operation returns a result or retained state that violates this contract: Return left-only then right-only unique values in their respective first-appearance orders.
Cartesian product order · case 01
The operation returns a result or retained state that violates this contract: Emit all ordered pairs in left-major, right-minor order, retaining duplicates.
Cartesian product order · case 02
The operation returns a result or retained state that violates this contract: Emit all ordered pairs in left-major, right-minor order, retaining duplicates.
Cartesian product order · case 03
The operation returns a result or retained state that violates this contract: Emit all ordered pairs in left-major, right-minor order, retaining duplicates.
Cartesian product order · case 04
The operation returns a result or retained state that violates this contract: Emit all ordered pairs in left-major, right-minor order, retaining duplicates.
Cartesian product order · case 05
The operation returns a result or retained state that violates this contract: Emit all ordered pairs in left-major, right-minor order, retaining duplicates.
Zip stops at shorter · case 01
The operation returns a result or retained state that violates this contract: Zip corresponding positions and stop at the shorter operand.
Zip stops at shorter · case 02
The operation returns a result or retained state that violates this contract: Zip corresponding positions and stop at the shorter operand.
Zip stops at shorter · case 03
The operation returns a result or retained state that violates this contract: Zip corresponding positions and stop at the shorter operand.
Zip stops at shorter · case 04
The operation returns a result or retained state that violates this contract: Zip corresponding positions and stop at the shorter operand.
Zip stops at shorter · case 05
The operation returns a result or retained state that violates this contract: Zip corresponding positions and stop at the shorter operand.
Zip longest explicit padding · case 01
The operation returns a result or retained state that violates this contract: Zip to the longer operand, using None for absent positions.
Zip longest explicit padding · case 02
The operation returns a result or retained state that violates this contract: Zip to the longer operand, using None for absent positions.
Zip longest explicit padding · case 03
The operation returns a result or retained state that violates this contract: Zip to the longer operand, using None for absent positions.
Zip longest explicit padding · case 04
The operation returns a result or retained state that violates this contract: Zip to the longer operand, using None for absent positions.
Zip longest explicit padding · case 05
The operation returns a result or retained state that violates this contract: Zip to the longer operand, using None for absent positions.
Alternating interleave preserves tail · case 01
The operation returns a result or retained state that violates this contract: Alternate left and right elements and retain the longer trailing suffix.
Alternating interleave preserves tail · case 02
The operation returns a result or retained state that violates this contract: Alternate left and right elements and retain the longer trailing suffix.
Alternating interleave preserves tail · case 03
The operation returns a result or retained state that violates this contract: Alternate left and right elements and retain the longer trailing suffix.
Alternating interleave preserves tail · case 04
The operation returns a result or retained state that violates this contract: Alternate left and right elements and retain the longer trailing suffix.
Alternating interleave preserves tail · case 05
The operation returns a result or retained state that violates this contract: Alternate left and right elements and retain the longer trailing suffix.
Subsequence not subset · case 01
The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.
Subsequence not subset · case 02
The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.
Subsequence not subset · case 03
The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.
Subsequence not subset · case 04
The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.
Subsequence not subset · case 05
The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.
Contiguous sublist search · case 01
The operation returns a result or retained state that violates this contract: Return whether right occurs as a contiguous sublist of left; empty right is always present.
Contiguous sublist search · case 02
The operation returns a result or retained state that violates this contract: Return whether right occurs as a contiguous sublist of left; empty right is always present.
Contiguous sublist search · case 03
The operation returns a result or retained state that violates this contract: Return whether right occurs as a contiguous sublist of left; empty right is always present.
Contiguous sublist search · case 04
The operation returns a result or retained state that violates this contract: Return whether right occurs as a contiguous sublist of left; empty right is always present.
Contiguous sublist search · case 05
The operation returns a result or retained state that violates this contract: Return whether right occurs as a contiguous sublist of left; empty right is always present.
Prefix compares positionally · case 01
The operation returns a result or retained state that violates this contract: Return whether right is a positional prefix of left.
Prefix compares positionally · case 02
The operation returns a result or retained state that violates this contract: Return whether right is a positional prefix of left.
Prefix compares positionally · case 03
The operation returns a result or retained state that violates this contract: Return whether right is a positional prefix of left.
Prefix compares positionally · case 04
The operation returns a result or retained state that violates this contract: Return whether right is a positional prefix of left.
Prefix compares positionally · case 05
The operation returns a result or retained state that violates this contract: Return whether right is a positional prefix of left.
INSPECTABLE BY DESIGN
Every result has a runnable source.
Runnable implementations with recorded outputs, source hashes, and explicit contracts. Related variants share a failure mechanism and belong together in evaluation splits.
Read the methodology ↗