Editing 1312: Haskell

{{comic
| number    = 1312
| date      = January 3, 2014
| title     = Haskell
| image     = haskell.png
| titletext = The problem with Haskell is that it's a language built on lazy evaluation and nobody's actually called for it.
}}

==Explanation==
The comic pokes fun at {{w|Haskell (programming language)|Haskell}}, a {{w|functional programming language}}.  Functional programming languages are based on the mathematical concept of a function.  Side effects are effects of a function other than returning a value.  As a simple example, if a <code>sum</code> function prints the sum before returning it, that is a side effect.  Real functions in most languages also have side effects, many of which are more complex, and sometimes hard to analyze.  Functional programming languages seek to avoid side effects when possible.  When side effects are required (for instance input and output), they are isolated to {{w|monad|monads}}, which are ways of representing sequential steps in functional programming.

The first joke is that Haskell only has no side effects merely because no one ever uses Haskell programs.  Even in a traditional procedural programming language like {{w|C (programming language)|C}}, no side effects can occur if the program does not run.

The title text describes Haskell's {{w|lazy evaluation}}.  The basic concept is that a value is not computed until it is actually used.  Thus, it is possible to have a variable representing the entire infinite list of {{w|Fibonacci numbers}}.  However, until a particular element of the list is accessed, no work is actually done.  Thus, the joke is that while Haskell may have potential, no one has "called" it (referencing calling a function), so nothing has actually been done.

In reality, Haskell is actively used, but not one of the most used languages.

==Transcript==
[Megan] Code written in Haskell is guaranteed to have no side effects. <br>
[Cueball] ... because no one will ever run it?
{{comic discussion}}