Functional programming is a style of programming which models computations as the evaluation of expressions. Functional Programming is when functions, not objects or procedures, are used as the fundamental building blocks of a program. Functions in this sense, not to be confused with 'C' language functions which are just procedures, are analogous to mathematical equations: they declare a relationship between two or more entities. Functional Programming, however, is not about mathematics but about abstraction and reducing complexity: as such, it provides a powerful paradigm in which to tackle complex, real-world programming tasks.
From pragmatic perspective, a beginner needs to understand only two concepts(Immutability and statelessness) in order to use it for everyday Functional Programming applications -
First, data in functional programs should be immutable, which sounds serious but just means that it should never change. At first, this might seem odd (after all, who needs a program that never changes anything?), but in practice, you would simply create new data structures instead of modifying ones that already exist. For example, if you need to manipulate some data in an array, then you’d make a new array with the updated values, rather than revise the original array. Easy!
Secondly, functional programs should be stateless, which basically means they should perform every task as if for the first time, with no knowledge of what may or may not have happened earlier in the program’s execution. Combined with immutability, this helps us think of each function as if it were operating in a vacuum, blissfully ignorant of anything else in the application besides other functions. In more concrete terms, this means that your functions will operate only on data passed in as arguments and will never rely on outside values to perform their calculations.
The special characteristics and advantages of functional programming are often summed up more or less as follows. Functional programs contain no assignment statements, so variables, once given a value, never change. More generally, functional programs contain no side-effects at all. A function call can have no effect other than to compute its result. This eliminates a major source of bugs, and also makes the order of execution irrelevant — since no side effect can change an expression’s value, it can be evaluated at any time. This relieves the programmer of the burden of prescribing the flow of control. Since expressions can be evaluated at any time, one can freely replace variables by their values and vice versa - that is, programs are “referentially transparent”.
Prominent functional programming languages are Scheme, Haskell, OCaml, Erlang, Clojure, Racket, F#, Common Lisp, Scala ..
ref:
Functional Programming - http://en.wikipedia.org/wiki/Functional_programming
Introduction to Functional programming - http://www.smashingmagazine.com/2014/07/02/dont-be-scared-of-functional-programming/
Why Functional Programming matters - http://www.cse.chalmers.se/~rjmh/Papers/whyfp.pdf, http://worrydream.com/refs/Hughes-WhyFunctionalProgrammingMatters.pdf
Conception, Evolution, and Application of Functional Programming Languages - http://www.utdallas.edu/~kXh060100/cs6301fa14/p359-hudak.pdf
Functional programming: A step backward - http://www.javaworld.com/article/2078610/java-concurrency/functional-programming--a-step-backward.html
erlang documentation - http://www.erlang.org/doc/pdf/otp-system-documentation.pdf
Haskell - http://www.haskell.org/haskellwiki/Haskell
Misc -
From pragmatic perspective, a beginner needs to understand only two concepts(Immutability and statelessness) in order to use it for everyday Functional Programming applications -
First, data in functional programs should be immutable, which sounds serious but just means that it should never change. At first, this might seem odd (after all, who needs a program that never changes anything?), but in practice, you would simply create new data structures instead of modifying ones that already exist. For example, if you need to manipulate some data in an array, then you’d make a new array with the updated values, rather than revise the original array. Easy!
Secondly, functional programs should be stateless, which basically means they should perform every task as if for the first time, with no knowledge of what may or may not have happened earlier in the program’s execution. Combined with immutability, this helps us think of each function as if it were operating in a vacuum, blissfully ignorant of anything else in the application besides other functions. In more concrete terms, this means that your functions will operate only on data passed in as arguments and will never rely on outside values to perform their calculations.
The special characteristics and advantages of functional programming are often summed up more or less as follows. Functional programs contain no assignment statements, so variables, once given a value, never change. More generally, functional programs contain no side-effects at all. A function call can have no effect other than to compute its result. This eliminates a major source of bugs, and also makes the order of execution irrelevant — since no side effect can change an expression’s value, it can be evaluated at any time. This relieves the programmer of the burden of prescribing the flow of control. Since expressions can be evaluated at any time, one can freely replace variables by their values and vice versa - that is, programs are “referentially transparent”.
Prominent functional programming languages are Scheme, Haskell, OCaml, Erlang, Clojure, Racket, F#, Common Lisp, Scala ..
ref:
Functional Programming - http://en.wikipedia.org/wiki/Functional_programming
Introduction to Functional programming - http://www.smashingmagazine.com/2014/07/02/dont-be-scared-of-functional-programming/
Why Functional Programming matters - http://www.cse.chalmers.se/~rjmh/Papers/whyfp.pdf, http://worrydream.com/refs/Hughes-WhyFunctionalProgrammingMatters.pdf
Conception, Evolution, and Application of Functional Programming Languages - http://www.utdallas.edu/~kXh060100/cs6301fa14/p359-hudak.pdf
Functional programming: A step backward - http://www.javaworld.com/article/2078610/java-concurrency/functional-programming--a-step-backward.html
erlang documentation - http://www.erlang.org/doc/pdf/otp-system-documentation.pdf
Haskell - http://www.haskell.org/haskellwiki/Haskell
Misc -
