F# Archives

Performance Test – SortedDictionary vs Dictionary vs Map vs Array

.Net, C#, F#, Functional Programming, Performance, Programming

I stumbled upon this interesting question on StackOverflow today, Jon Harrop’s answer mentions a significant overhead in adding and iterating over a SortedDictionary and Map compared to using simple arrays. Thinking about it, this makes sense, the SortedDictionary class sorts its constituent key-value pairs by key, which will naturally incur some performance overhead. F#’s Map …

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Project Euler – Problem 65 Solution

.Net, F#, Functional Programming, Learning F#, Programming, Project Euler Solutions

Problem The square root of 2 can be written as an infinite continued fraction. The infinite continued fraction can be written, ?2 = [1;(2)], (2) indicates that 2 repeats ad infinitum. In a similar way, ?23 = [4;(1,3,1,8)]. It turns out that the sequence of partial values of continued fractions for square roots provide the …

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Project Euler – Problem 71 Solution

.Net, F#, Functional Programming, Learning F#, Programming, Project Euler Solutions

Problem Consider the fraction, n/d, where n and d are positive integers. If n < d and HCF(n,d)=1, it is called a reduced proper fraction. If we list the set of reduced proper fractions for d <= 8 in ascending order of size, we get: 1/8, 1/7, 1/6, 1/5, 1/4, 2/7, 1/3, 3/8, 2/5, 3/7, …

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F# – Adding custom indexer and slicer to your type

.Net, F#, Functional Programming, Programming, Tips

Indexer If your have a type that represents a collection of values, adding a custom indexer gives you a natural way to index directly into the object using the .[ ] operator. Take this simple Calendar class for instance, which keeps a map (F# equivalent of a Dictionary<TKey, TValue>) of notes against DateTime values: By …

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Use F# to meet your scripting needs

.Net, F#, Functional Programming, Programming

Normally, with languages like C# or Java, there is quite a bit of overhead in creating a quick and dirty program to do small tasks like bulk renaming files in a director, etc. This is the spot that is filled by scripting languages like Python, Perl and Ruby, but did you know that you can …

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AOP with F# – Memoization using higher-order functions

.Net, Aspect Oriented Programming, F#, Functional Programming, Programming

I touched on the topic of memoization in the past in relation to doing aspect-oriented programming with PostSharp, however, with functional languages like F#, Haskell or Erlang there is no such frameworks (although PostSharp should still work with F# to some extent) to help you. That’s not to say that you can’t do AOP in …

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F# Performance Test – Structs vs Records

.Net, F#, Functional Programming, Performance, Programming

In F#, you have the choice of using a struct or a record as a lightweight container for data. The similarities between the two are striking – both are immutable by default, neither can be inherited, and they both offer structural equality semantics by default too! However, there’s a key difference between them, their performance …

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F# – Enums vs Discriminated Unions

.Net, F#, Functional Programming, Performance, Programming

In my previous post on discriminated unions, I presented discriminated unions as an alternative to standard .Net classes to represent hierarchical data structures. However, in terms of data structure, discriminated unions share much more similarities with enums than they do classes – both allow you to define a set of named constants and associate some …

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F# – Referential equality for tuples, discriminated unions and records

.Net, F#, Functional Programming, Programming

By default, tuples, discriminated unions and records have what is known as structural equality – i.e. if two instances of these types have the same set of values then they are considered equal, just like value types – despite being reference types: Tuples Discriminated Unions Records To facilitate this form of equality, the F# compiler …

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F# – Exception handling the pattern matching way!

.Net, F#, Functional Programming, Programming

Pattern matching is everywhere in F#, you can use it in let bindings, in function parameters, in for loops, everywhere, and it is totally amazing. It is in my opinion one of the best features of F#, and in functional languages in general, heck, Erlang goes as far as not having an assignment operator and …

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