Down with variables

• Author(s): Cunha, Alcino ; Pinto, Jorge Sousa ; Proença, Alberto José
• Date: 2005
• Persistent ID: http://hdl.handle.net/1822/2759
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Functional programming; Point-free programming; Haskell
• Document Type: Report
• Language: English

Description

Techn. Report DI-PURe-05.06.01 The subject of this paper is point-free functional programming in Haskell. By this we mean writing programs using categorically-inspired combinators, algebraic data types defined as fixed points of functors, and impicit recursion through the use of type-parameterized recursion patterns. This style of programming is appropriate for program calculation (reasoning about programs equationally), but difficult to actually use in practice - most programmers use a mixture of the above elements with explicit recursion and manipulation of arguments. In this paper we present a mechanism that allows programmers to convert classic point-wise code into point-free style, and a Haskell library that enables the direct execution of the resulting code. Together, they make possible the use of point-free either as a direct programming style or as a domain into which programs can be transformed before being subject to further manipulation.