research-article

Type-level web APIs with Servant: an exercise in domain-specific generic programming

Authors:

Alp Mestanogullari,

Sönke Hahn,

Julian K. Arni,

Andres LöhAuthors Info & Claims

WGP 2015: Proceedings of the 11th ACM SIGPLAN Workshop on Generic Programming

Pages 1 - 12

https://doi.org/10.1145/2808098.2808099

Published: 30 August 2015 Publication History

Get Access

Abstract

We describe the design and motivation for Servant, an extensible, type-level DSL for describing Web APIs. Servant APIs are Haskell types. An API type can be interpreted in several different ways: as a server that processes requests, interprets them and dispatches them to appropriate handlers; as a client that can correctly query the endpoints of the API; as systematic documentation for the API; and more. Servant is fully extensible: the API language can be augmented with new constructs, and new interpretations can be defined. The key Haskell features making all this possible are data kinds, (open) type families and (open) type classes. The techniques we use are reminiscent of general-purpose generic programming. However, where most generic programming libraries are interested in automatically deriving programs for a large class of datatypes from many different domains, we are only interested in a small class of datatypes that is used in the DSL for describing APIs.

References

[1]

T. Altenkirch and C. McBride. Generic programming within dependently typed programming. In IFIP TC2/WG2.1 WGP, pages 1–20. Kluwer, 2003.

Digital Library

Google Scholar

[2]

P. Bahr and T. Hvitved. Compositional data types. In WGP 2011, pages 83–94. ACM, 2011.

Digital Library

Google Scholar

[3]

API Blueprint: Format 1A Revision 8. URL https://github. com/apiaryio/api-blueprint/blob/master/API%20Blueprint% 20Specification.md. Accessed: 2015-07-19. J. Carette, O. Kiselyov, and C.-c. Shan. Finally tagless, partially evaluated: Tagless staged interpreters for simpler typed languages. Journal of Functional Programming, 19:509–543, Sept. 2009.

Digital Library

Google Scholar

[4]

M. M. T. Chakravarty, G. C. Ditu, and R. Leshchinskiy. Instant generics: Fast and easy. Accessed: 2015-07-19. URL https://www.cse.unsw. edu.au/~chak/papers/CDL09.html. E. Christensen, F. Curbera, G. Meredith, and S. Weerawarana. Web Services Description Language ( WSDL ) 1.1, Mar. 2001. URL http://www.w3. org/TR/wsdl. Accessed: 2015-07-19. E. de Vries and A. Löh. True sums of products. In WGP 2014, pages 83–94. ACM, 2014.

Google Scholar

[5]

C. Dornan and A. Gundry. api-tools. URL https://hackage.haskell. org/package/api-tools. Accessed: 2015-07-19. R. A. Eisenberg and S. Weirich. Dependently typed programming with singletons. In Haskell 2012, pages 117–130. ACM, 2012.

Digital Library

Google Scholar

[6]

M. Fischmann and A. Löh. configifier, 2015. URL https://hackage. haskell.org/package/configifier. Accessed: 2015-07-19. N. Freed and N. Borenstein. Multipurpose internet mail extensions ( MIME ) part two: Media types, Nov. 1996. URL http://tools.ietf.org/ html/rfc2046. Happstack Team. happstack-server. URL https://hackage.haskell. org/package/happstack-server. Accessed: 2015-07-19. S. Holdermans, J. Jeuring, A. Löh, and A. Rodriguez. Generic views on data types. In MPC 2006, pages 209–234. Springer-Verlag, 2006.

Digital Library

Google Scholar

[7]

R. Lämmel and K. Ostermann. Software extension and integration with type classes. In GPCE 2006, pages 161–170. ACM, 2006.

Digital Library

Google Scholar

[8]

rest-core. URL https://hackage.haskell.org/package/rest-core. Accessed: 2015-07-19. J. C. Reynolds. User-defined types and procedural data structures as complementary approaches to data abstraction. In S. A. Schuman, editor, New Directions in Algorithmic Languages, pages 157–168. INRIA, 1975.

Google Scholar

[9]

A. Rodriguez, J. Jeuring, P. Jansson, A. Gerdes, O. Kiselyov, and B. C. d. S. Oliveira. Comparing libraries for generic programming in Haskell. In Haskell 2008, pages 111–122. ACM, 2008.

Digital Library

Google Scholar

[10]

servant – Webservice API combinators. URL https://haskell-servant. github.io. Accessed: 2015-07-19. M. Snoyman. Developing Web Applications with Haskell and Yesod. O’Reilly Media, Apr. 2012.

Google Scholar

[11]

S. D. Swierstra and L. Duponcheel. Deterministic, error-correcting combinator parsers. In Advanced Functional Programming, volume 1129 of LNCS, pages 184–207. Springer-Verlag, 1996.

Digital Library

Google Scholar

[12]

W. Swierstra. Data types à la carte. Journal of Functional Programming, 18(4):423–436, July 2008.

Digital Library

Google Scholar

[13]

The RAML Workgroup. RAML ™ version 0.8: REST ful API modeling. URL http://raml.org/spec.html. Accessed: 2015-07-19. P. Wadler. The expression problem, Nov. 1998. URL http://homepages. inf.ed.ac.uk/wadler/papers/expression/expression.txt. Email to the java-genericity mailing list. B. A. Yorgey, S. Weirich, J. Cretin, S. Peyton Jones, D. Vytiniotis, and J. P. Magalhães. Giving Haskell a promotion. In TLDI 2012, pages 53–66. ACM, 2012.

Digital Library

Google Scholar

Cited By

View all

Keating FGale MVazou NMorris J(2024)Functional Reactive Programming, RearrangedProceedings of the 17th ACM SIGPLAN International Haskell Symposium10.1145/3677999.3678278(55-67)Online publication date: 29-Aug-2024
https://dl.acm.org/doi/10.1145/3677999.3678278
Crichton WSperber MHutton G(2023)Typed Design Patterns for the Functional EraProceedings of the 1st ACM SIGPLAN International Workshop on Functional Software Architecture10.1145/3609025.3609477(40-48)Online publication date: 30-Aug-2023
https://dl.acm.org/doi/10.1145/3609025.3609477
Shen GKashiwa SKuper L(2023)HasChor: Functional Choreographic Programming for All (Functional Pearl)Proceedings of the ACM on Programming Languages10.1145/36078497:ICFP(541-565)Online publication date: 30-Aug-2023
https://dl.acm.org/doi/10.1145/3607849
Show More Cited By

Index Terms

Type-level web APIs with Servant: an exercise in domain-specific generic programming
1. Software and its engineering
  1. Software notations and tools
    1. General programming languages
      1. Language types
        Functional languages

Recommendations

Generic record combinators with static type checking
PPDP '10: Proceedings of the 12th international ACM SIGPLAN symposium on Principles and practice of declarative programming

Common record systems only provide access to individual record fields. However, it is often useful to have generic record combinators, that is, functions that work with complete records of varying structure. Traditionally, generic record combinators can ...
Injective type families for Haskell
Haskell '15: Proceedings of the 2015 ACM SIGPLAN Symposium on Haskell

Haskell, as implemented by the Glasgow Haskell Compiler (GHC), allows expressive type-level programming. The most popular type-level programming extension is TypeFamilies, which allows users to write functions on types. Yet, using type functions can ...
Injective type families for Haskell
Haskell '15

Haskell, as implemented by the Glasgow Haskell Compiler (GHC), allows expressive type-level programming. The most popular type-level programming extension is TypeFamilies, which allows users to write functions on types. Yet, using type functions can ...

Comments

Please enable JavaScript to view thecomments powered by Disqus.

Information & Contributors

Information

Published In

WGP 2015: Proceedings of the 11th ACM SIGPLAN Workshop on Generic Programming

August 2015

44 pages

ISBN:9781450338103

DOI:10.1145/2808098

Program Chairs:
Patrick Bahr,
Sebastian Erdweg

Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from [email protected].

Publisher

Association for Computing Machinery

New York, NY, United States

Publication History

Published: 30 August 2015

Permissions

Request permissions for this article.

Request Permissions

Check for updates

Author Tags

Qualifiers

Research-article

Conference

ICFP'15

Sponsor:

SIGPLAN

ICFP'15: 20th ACM SIGPLAN International Conference on Functional Programming

August 30, 2015

BC, Vancouver, Canada

Acceptance Rates

Overall Acceptance Rate 30 of 43 submissions, 70%

Upcoming Conference

ICFP '25

Sponsor:
sigplan

ACM SIGPLAN International Conference on Functional Programming

October 12 - 18, 2025

Singapore , Singapore

Contributors

Other Metrics

View Article Metrics

Bibliometrics & Citations

Bibliometrics

Article Metrics

8
Total Citations
View Citations
710
Total Downloads

Downloads (Last 12 months)28
Downloads (Last 6 weeks)5

Reflects downloads up to 10 Nov 2024

Other Metrics

View Author Metrics

Citations

Cited By

View all

Keating FGale MVazou NMorris J(2024)Functional Reactive Programming, RearrangedProceedings of the 17th ACM SIGPLAN International Haskell Symposium10.1145/3677999.3678278(55-67)Online publication date: 29-Aug-2024
https://dl.acm.org/doi/10.1145/3677999.3678278
Crichton WSperber MHutton G(2023)Typed Design Patterns for the Functional EraProceedings of the 1st ACM SIGPLAN International Workshop on Functional Software Architecture10.1145/3609025.3609477(40-48)Online publication date: 30-Aug-2023
https://dl.acm.org/doi/10.1145/3609025.3609477
Shen GKashiwa SKuper L(2023)HasChor: Functional Choreographic Programming for All (Functional Pearl)Proceedings of the ACM on Programming Languages10.1145/36078497:ICFP(541-565)Online publication date: 30-Aug-2023
https://dl.acm.org/doi/10.1145/3607849
Redmond PShen GVazou NKuper L(2022)Verified Causal Broadcast with Liquid HaskellProceedings of the 34th Symposium on Implementation and Application of Functional Languages10.1145/3587216.3587222(1-13)Online publication date: 31-Aug-2022
https://dl.acm.org/doi/10.1145/3587216.3587222
Koopman PMichels SPlasmeijer R(2021)Dynamic Editors for Well-Typed ExpressionsTrends in Functional Programming10.1007/978-3-030-83978-9_3(44-66)Online publication date: 23-Aug-2021
https://doi.org/10.1007/978-3-030-83978-9_3
Serrano ACorpa FSchrijvers T(2020)Describing microservices using modern Haskell (experience report)Proceedings of the 13th ACM SIGPLAN International Symposium on Haskell10.1145/3406088.3409018(1-8)Online publication date: 27-Aug-2020
https://dl.acm.org/doi/10.1145/3406088.3409018
Algehed MJansson PEinarsdóttir SGerdes A(2019)Saint: An API-Generic Type-Safe InterpreterZivilgesellschaft und Wohlfahrtsstaat im Wandel10.1007/978-3-030-18506-0_5(94-113)Online publication date: 24-Apr-2019
https://doi.org/10.1007/978-3-030-18506-0_5
Miraldo VCarr HKogan AMoir MHerlihy MEisenberg RVazou N(2018)Authenticated modular maps in HaskellProceedings of the 3rd ACM SIGPLAN International Workshop on Type-Driven Development10.1145/3240719.3241790(1-13)Online publication date: 27-Sep-2018
https://dl.acm.org/doi/10.1145/3240719.3241790

View Options

Get Access

Login options

Check if you have access through your login credentials or your institution to get full access on this article.

Cited By

Index Terms

Recommendations

Generic record combinators with static type checking

Injective type families for Haskell

Injective type families for Haskell