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 …
F# – Adding custom indexer and slicer to your type Read More »
To install pip on Windows, you need to first install its predecessor – easy install. However, if you’re using a 64-bit distribution of Python then the .exe installers here will give you this error when you run it: This is due to a distutils installer compatibility issue, but all’s not lost, you just need to …
Just a quick note to mention that I will be speaking to local user groups about Aspect Oriented Programming next month: Nov 16th – The Developers Group http://LNK.by/fimbc Nov 17th – NxtGenUG Southampton http://LNK.by/fimbb The session will offer you a high-level overview of AOP and give you some ideas on how it might help you …
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 …
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 …
AOP with F# – Memoization using higher-order functions Read More »
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 …
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 …
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 …
F# – Referential equality for tuples, discriminated unions and records Read More »
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 …
F# – Exception handling the pattern matching way! Read More »
Ayande posted a tax calculation challenge the other day here, and here’s my F# solution for the challenge: Enjoy!
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