Functional programming: Difference between revisions
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imported>Howard C. Berkowitz (Headings and references; copy edit) |
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A '''functional programming''' language is a language modeled after mathematical functions. Non-functional computer programs allow state changes. | |||
==First class data types== | |||
First class data types | |||
Functional programs typically make functions first class data types. This | Functional programs typically make functions first class data types. This | ||
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allows for the creation of higher order functions(functions of functions). | allows for the creation of higher order functions(functions of functions). | ||
Input/Output | ==Input/Output== | ||
In functional programming state is not saved | In functional programming state is not saved | ||
outside of function calls due to restrictions on | outside of function calls due to restrictions on input/output calls (I/O) | ||
State may not change during a function call. Restricting | State may not change during a function call. Restricting I/O | ||
protects | protects against side effects, such as bad distant changes I/O caused by local computation . | ||
Single assignment and proofs | ==Single assignment and proofs== | ||
Single assignment makes a computation into a dataflow. Dataflows are easy for | Single assignment makes a computation into a dataflow. Dataflows are easy for | ||
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Some functional programs can be proved to be equal to each other or | Some functional programs can be proved to be equal to each other or | ||
proved to be stable under certain conditions. Such proofs can aid | proved to be stable under certain conditions. Such proofs can aid | ||
the efforts of software engineers and computer scientists. | the efforts of software engineers and computer scientists. <ref>{{citation | ||
| author = Graham Hutton, 1999 | |||
| url = http://www.cs.nott.ac.uk/~gmh/fold.pdf | |||
| title = A tutorial on the universality and expressiveness of fold | |||
| journal = J. Functional Programming | volume = 9 | issue = 4 | pages =355–372 | date = July 1999}}</ref> | |||
Some examples of functional programming languages are: | Some examples of functional programming languages are: | ||
*[[scheme_programming_language|Scheme]], | |||
*[[erlang_programming_language|Erlang]], (excluding all parallel functions) | |||
*[[haskell_programming_language|Haskell]]. | |||
If a functional language is eager then all values are fully computed in the order that they are encountered. In a lazy language like | If a functional language is eager then all values are fully computed in the order that they are encountered. In a lazy language like Haskell | ||
some arguments are allowed to have delayed evaluation. | some arguments are allowed to have delayed evaluation. | ||
==References== | |||
{{reflist}} | |||
Latest revision as of 15:18, 25 January 2011
A functional programming language is a language modeled after mathematical functions. Non-functional computer programs allow state changes.
First class data types
Functional programs typically make functions first class data types. This allows functions to be passes as arguments to other functions and allows for the creation of higher order functions(functions of functions).
Input/Output
In functional programming state is not saved outside of function calls due to restrictions on input/output calls (I/O) State may not change during a function call. Restricting I/O protects against side effects, such as bad distant changes I/O caused by local computation .
Single assignment and proofs
Single assignment makes a computation into a dataflow. Dataflows are easy for compilers to understand. When state is fixed, functions can be treated similar to mathematical functions and facts can be proved about such functions. Some functional programs can be proved to be equal to each other or proved to be stable under certain conditions. Such proofs can aid the efforts of software engineers and computer scientists. [1] Some examples of functional programming languages are:
If a functional language is eager then all values are fully computed in the order that they are encountered. In a lazy language like Haskell some arguments are allowed to have delayed evaluation.
References
- ↑ Graham Hutton, 1999 (July 1999), "A tutorial on the universality and expressiveness of fold", J. Functional Programming 9 (4): 355–372