The Shape of Code

Yesterday I was at the British Standards Institute for a meeting of the programming languages committee. Some highlights and commentary:

• The first Technical Corrigendum (bug fixes, 47 of them) for Fortran 2008 was approved.
• The Lisp Standard working group was shutdown, through long standing lack of people interested in taking part; this happened at the last SC22 meeting, the UK does not have such sole authority.
• WG14 (C Standard) has requested permission to start a new work item to create a new annex to the standard containing a Secure Coding Standard. Isn’t this the area of expertise of WG23 (Language vulnerabilities)? Well, yes; but when the US Department of Homeland Security is throwing money at cyber security increasing the number of standards’ groups working on the topic creates more billable hours for consultants.
• WG21 (C++ Standard) had 73 people at their five day meeting last week (ok, it was in Hawaii). Having just published a 1,300+ page Standard which no compiler yet comes close to implementing they are going full steam ahead creating new features for a revised standard they aim to publish in 2017. Does the “Hear about the upcoming features in C++” blogging/speaker circuit/consulting gravy train have that much life left in it? We will see.

The BSI building has new lifts (elevators in the US). To recap, lifts used to work by pressing a button to indicate a desire to change floors, a lift would arrive, once inside one or more people needed press buttons specifying destination floor(s). Now the destination floor has to be specified in advance, a lift arrives and by the time you have figured out there are no buttons to press on the inside of the lift the doors open at the desired floor. What programming language most closely mimics this new behavior?

Mimicking most languages of the last twenty years the ground floor is zero (I could not find any way to enter a G). This rules out a few languages, such as Fortran and R.

A lift might be thought of as a function that can be called to change floors. The floor has to be specified in advance and cannot be changed once in the lift, partial specialization of functions and also the lambda calculus springs to mind.

In a language I just invented:

// The lift specified a maximum of 8 people
lift = function(p_1, p_2="", p_3="", p_4="", p_5="", p_6="", p_7="", p_8="") {...}
// Meeting was on the fifth floor
first_passenger_5th_floor = function lift(5);
second_passenger_4th_floor = function first_passenger_fifth_floor(4);

the body of the function second_passenger_4th_floor is a copy of the body of lift with all the instances of p_1 and p_2 replaced by the 5 and 4 respectively.

Few languages have this kind of functionality. The one that most obviously springs to mind is Lisp (partial specialization of function templates in C++ does not count because they are templates that are still in need of an instantiation). So the ghost of the Lisp working group lives on at BSI in their lifts.