| 1. |
- Ahn, Ki Yung, et al.
(author)
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Executable relational specifications of polymorphic type systems using prolog
- 2016
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319296036 ; 9613, s. 109-125
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Conference paper (peer-reviewed)abstract
- A concise, declarative, and machine executable specification of the Hindley–Milner type system (HM) can be formulated using logic programming languages such as Prolog. Modern functional language implementations such as the Glasgow Haskell Compiler support more extensive flavors of polymorphism beyond Milner’s theory of type polymorphism in the late 70's. We progressively extend the HM specification to include more advanced type system features. An interesting development is that extending dimensions of polymorphism beyond HM resulted in a multi-staged solution: resolve the typing relations first, while delaying to resolve kinding relations, and then resolve the delayed kinding relations. Our work demonstrates that logic programing is effective for prototyping polymorphic type systems with rich features of polymorphism, and that logic programming could have been even more effective for specifying type inference if it were equipped with better theories and tools for staged resolution of different relations at different levels.
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| 2. |
- Axelsson, Emil, 1978, et al.
(author)
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Lightweight Higher-Order Rewriting in Haskell
- 2016
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; 9547, s. 1-21
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Conference paper (peer-reviewed)abstract
- We present a generic Haskell library for expressing rewrite rules with a safe treatment of variables and binders. Both sides of the rules are written as typed EDSL expressions, which leads to syntactically appealing rules and hides the underlying term representation. Matching is defined as an instance of Miller's higher-order pattern unification and has the same complexity as first-order matching. The restrictions of pattern unification are captured in the types of the library, and we show by example that the library is capable of expressing useful simplifications that might be used in a compiler.
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| 3. |
- Birkedal, Lars, et al.
(author)
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Guarded Cubical Type Theory: Path Equality for Guarded Recursion
- 2016
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In: Leibniz International Proceedings in Informatics, LIPIcs. - 1868-8969. - 9783959770224 ; 62, s. 23:1-23:17
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Conference paper (peer-reviewed)abstract
- This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning with coinductive types. We wish to implement GDTT with decidable type checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-Löf type theory in which the identity type is replaced by abstract paths between terms. CTT provides a computational interpretation of functional extensionality, is conjectured to have decidable type checking, and has an implemented type checker. Our new type theory, called guarded cubical type theory, provides a computational interpretation of extensionality for guarded recursive types. This further expands the foundations of CTT as a basis for formalisation in mathematics and computer science. We present examples to demonstrate the expressivity of our type theory, all of which have been checked using a prototype type-checker implementation, and present semantics in a presheaf category.
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