eta-case example #242
eta-case example #242
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Actionable comments posted: 4
Outside diff range and nitpick comments (3)
examples/eta-case.kl (3)
17-22: Consider enhancing readability through comments within thelist-to-pairfunction.The function
list-to-pairconverts a list to a pair. It would benefit from additional inline comments explaining the logic, especially for those unfamiliar with Klister's pattern matching syntax.
32-37: Document the hypothetical scenario for better clarity.The block comments from lines 32 to 37 introduce a hypothetical enhancement inspired by Haskell. More detailed comments explaining how this would translate into practical enhancements in Klister could help maintainers and new contributors understand the intent and utility of the proposed changes.
39-44: Clarify the commented-outeta-list-to-pairfunction.The commented-out example of
eta-list-to-pairon lines 39 to 44 is crucial for understanding the proposedeta-casefeature. It would be helpful to include an explanation of why this example is commented out and how it relates to the actual implementation that follows.
Review details
Configuration used: CodeRabbit UI
Review profile: CHILL
Files selected for processing (2)
- examples/eta-case.golden (1 hunks)
- examples/eta-case.kl (1 hunks)
Files skipped from review due to trivial changes (1)
- examples/eta-case.golden
Additional comments not posted (2)
examples/eta-case.kl (2)
80-91: Validate the conceptual explanation ofeta-case.The explanation from lines 80 to 91 about
eta-casebeing a macro which expands to a function application is intricate. It would be prudent to validate this explanation with additional examples or unit tests to ensure that the concept is implemented correctly and is understandable.Verification successful
Validate the conceptual explanation of
eta-case.The search results indicate multiple occurrences of
eta-casein theexamples/eta-case.klfile. This file contains detailed comments and examples that align with the conceptual explanation provided in lines 80-91. The examples and comments in this file should help validate the explanation ofeta-caseas a macro that expands to a function application.
- File:
examples/eta-case.kl
- Contains multiple references to
eta-caseandeta-case-aux.- Includes detailed comments explaining the functionality and providing examples.
Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Search for additional examples or tests related to `eta-case`. # Test: Find occurrences of `eta-case` usage in test files. Expect: Examples or tests validating its behavior. rg --type kl 'eta-case' --files-with-matches | xargs catLength of output: 83
Script:
#!/bin/bash # Step 1: Find all `.kl` files in the repository. fd -e kl > kl_files.txt # Step 2: Search for `eta-case` within those files. xargs rg 'eta-case' < kl_files.txtLength of output: 3421
409-412: Validate new functioneta-list-to-pair.The newly introduced function
eta-list-to-pairon lines 409 to 412 simplifies pattern matching by usingeta-case. It is essential to ensure that this function is thoroughly tested to confirm its correctness and efficiency.Verification successful
Function
eta-list-to-pairis implemented and examples are present.The function
eta-list-to-pairis defined inexamples/eta-case.kl. Additionally, there are examples present in the same file that appear to test this function with different inputs. This suggests that the function is implemented and there are some tests to verify its correctness.
examples/eta-case.kl:
- Definition:
(defun eta-list-to-pair (xs0)- Examples:
(example (eta-list-to-pair (list))),(example (eta-list-to-pair (list 1 2 3)))Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Verify the implementation of `eta-list-to-pair`. # Test: Search for the function usage and its tests. Expect: Proper implementation and corresponding unit tests. rg --type kl 'eta-list-to-pair' --files-with-matches | xargs catLength of output: 91
Script:
#!/bin/bash # Search for the definition of the `eta-list-to-pair` function ast-grep --lang clojure --pattern $'(defun eta-list-to-pair $_)' # Search for test cases involving `eta-list-to-pair` rg 'eta-list-to-pair' --type-add 'clojure:*.kl'Length of output: 455
Script:
#!/bin/bash # Locate the definition of the `eta-list-to-pair` function in examples/eta-case.kl rg 'defun eta-list-to-pair' examples/eta-case.kl # Verify test cases or examples for `eta-list-to-pair` in examples/eta-case.kl rg 'eta-list-to-pair' examples/eta-case.klLength of output: 301
| (meta -- meta makes the definitions in this block available inside of macro | ||
| -- definitions, such as the definition of eta-case-aux. | ||
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| -- First, let's extract the type of (::). We are working in the Macro monad, | ||
| -- whose (which-problem) primitive allows us to figure out the type of the | ||
| -- function | ||
| -- (eta-case-aux ...) | ||
| -- in the context of this function application. | ||
| -- ((eta-case-aux ...) (::)) | ||
| -- The type of (eta-case-aux ...) must thus be | ||
| -- (-> <the-type-of-::> <some-output-type>) | ||
| -- And from that we can extract the type of (::). | ||
| -- | ||
| -- (>>= get-type-of-lhs | ||
| -- (lambda (type) ...)) | ||
| -- => | ||
| -- type = (-> a (list a) (list a)) | ||
| (define get-type-of-lhs |
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Review the macro definitions within the meta block for clarity and correctness.
The macro definitions starting from line 95 are critical for the functionality of eta-case. Each macro should be thoroughly reviewed to ensure they are correctly capturing and manipulating types as intended. This is especially important since macros can introduce subtle bugs if not handled carefully.
| -- | ||
| -- (add-temporaries-list 2 (list '::) (list 'pair)) | ||
| -- => | ||
| -- (pair (list ':: 'x1 'x2) (list 'pair 'x1 'x2)) | ||
| (defun add-temporaries-list (n lhs rhs) | ||
| (if (<= n 0) | ||
| (pure (pair lhs rhs)) | ||
| (>>= (make-temporary 'x) | ||
| (lambda (varname) | ||
| (>>= (add-temporaries-list (- n 1) lhs rhs) | ||
| (lambda (extended-lhs-and-rhs) | ||
| (case extended-lhs-and-rhs | ||
| [(pair extended-lhs extended-rhs) | ||
| (pure (pair (snoc extended-lhs varname) | ||
| (snoc extended-rhs varname)))]))))))) |
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Simplify the add-temporaries-list function.
The function add-temporaries-list on lines 139 to 153 is complex and could be simplified. Consider refactoring it to improve readability and maintainability, possibly by breaking it down into smaller, more focused functions.
| -- Next, let's generate the call to case. | ||
| -- | ||
| -- The stx argument is used to attach the line number of the eta-case call, so | ||
| -- that error messages point at that call site instead of this mk-case-call | ||
| -- definition. | ||
| -- | ||
| -- The eta-case argument is the name of the eta-case macro, which will be in | ||
| -- scope at the call site of mk-case-call but is not in scope here. | ||
| (define mk-case-call | ||
| (the (-> Syntax Syntax Syntax Syntax Syntax (List Syntax) Syntax) | ||
| (lambda (stx eta-case scrutinee lhs rhs patterns) | ||
| `(case ,scrutinee | ||
| [,lhs ,rhs] | ||
| [(else evaluated-scrutinee) | ||
| ,(close-syntax stx stx | ||
| (list-contents | ||
| (:: eta-case | ||
| (:: 'evaluated-scrutinee | ||
| patterns))))])))) |
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Ensure robust error handling in mk-case-call.
The function mk-case-call from lines 177 to 195 generates a case call dynamically. It is crucial to ensure that this function handles errors robustly, especially given its dynamic nature and the complexity of the syntax manipulations it performs.
| -- macros. | ||
| (define-macros ( | ||
| -- (eta-case (list 1 2 3) | ||
| -- [(::) (pair)] | ||
| -- [(nil) (pair 0 (nil))]) | ||
| -- => | ||
| -- (eta-case-aux (list 1 2 3) | ||
| -- (::) | ||
| -- (pair) | ||
| -- [(nil) (pair 0 (nil))]) | ||
| [eta-case | ||
| (lambda (stx) | ||
| (case (open-syntax stx) | ||
| [(list-contents | ||
| (:: _eta-case (:: scrutinee (nil)))) | ||
| (pure `(case ,scrutinee))] | ||
| [(list-contents | ||
| (:: _eta-case (:: scrutinee (:: branch branches)))) | ||
| (case (open-syntax branch) | ||
| [(list-contents | ||
| (:: lhs (:: rhs (nil)))) | ||
| (pure (mk-apply | ||
| (mk-aux-call stx 'eta-case-aux scrutinee lhs rhs branches) | ||
| lhs))])]))] | ||
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| -- ((eta-case-aux (list 1 2 3) | ||
| -- (::) | ||
| -- (pair) | ||
| -- [(nil) (pair 0 (nil))]) | ||
| -- (::)) | ||
| -- => | ||
| -- ((lambda (_) | ||
| -- (case (list 1 2 3) | ||
| -- [(:: x1 x2) (pair x1 x2)] | ||
| -- [(else scrutinee) | ||
| -- (eta-case scrutinee | ||
| -- [(nil) (pair 0 (nil))])])) | ||
| -- (::)) | ||
| [eta-case-aux | ||
| (lambda (stx) | ||
| (>>= get-type-of-lhs | ||
| (lambda (type) | ||
| (>>= (type-arity type) | ||
| (lambda (n) | ||
| (case (open-syntax stx) | ||
| [(list-contents | ||
| (:: _eta-case-aux (:: scrutinee (:: lhs (:: rhs branches))))) | ||
| (>>= (add-temporaries-stx n lhs rhs) | ||
| (lambda (extended-lhs-and-rhs) | ||
| (case extended-lhs-and-rhs | ||
| [(pair extended-lhs extended-rhs) | ||
| (pure (mk-lambda | ||
| (mk-case-call stx 'eta-case scrutinee | ||
| extended-lhs extended-rhs | ||
| branches)))])))]))))))])) |
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Assess the implementation of eta-case and eta-case-aux macros.
The definitions of eta-case and eta-case-aux macros from lines 255 to 309 are central to the new functionality introduced in this file. These should be closely reviewed to ensure they meet the intended design goals, especially in terms of type safety and macro expansion correctness.
Demonstrating Klister's usefulness by implementing a feature which was imagined for Haskell on Twitter.
Summary by CodeRabbit
New Features
eta-casein Klister to enable eta-reduction in pattern-matching, enhancing code conciseness and readability.Refactor
defun list-to-pair (xs0)todefun eta-list-to-pair (xs0).defun eta-list-to-pair (xs0).