Ick

Tue, 11 Mar 2008 15:23:55 +0000

Okay suppress your gagging reflex. Ick is actually the Invocation Construction Kit by Reginald Braithwaite which is a kit for building language abstractions like #andand, #if_not_nil, and #try in a more structured way.

For example a common pattern in code is:

x = some_expr
do_something_with( x )

There's nothing inherently wrong with this code but it leaves x in scope past the point where it's needed and, implicit in that, is that it's a little harder to separate the expression using x from the code around it if we want to refactor it later on.

Ick defines #let() for exactly this purpose:

let( someexpr ) { |x| dosomething_with( x ) }

In this example it's very clear what the required scope is for x and that it can be moved without affecting other code (obviously taking into account if the return value for let is used).

Now lots of people are defining methods like #let and #maybe, so how is Ick different? It's different in the way #let is defined:

class Let < Base
  evaluates_in_calling_environment and returns_result
end

There is some magic going on by which this Let class is used through a method on Object but ignoring that, the definition of #let is in terms of fundamental operations of evaluation. Ick has abstracted what it means to evaluate an expression.

By the same means other forms such as #try and #maybe are built up. If you want to create a new abstraction you can build it from the building blocks like evaluates_in_value_environment and create new building blocks.

Ick seems to me to be a very powerful tool for Ruby programmers.

Curiouser and Curiouser! on monads

Ick