A blog about teaching Programming to non-CompSci students by Tim Love (Cambridge University Engineering Department). I do not speak on behalf of the university, the department, or even the IT group I belong to.

Wednesday, 24 December 2014

"Geek Sublime" by Vikram Chandra (Faber and Faber, 2014)

The author's written some very respectable novels and stories, but he was also a programmer and a computer consultant - a self-confessed geek. The blurb says "What is the relationship between the two? Is there such a thing as the sublime in code? Can we ascribe beauty to the craft of coding?" but only a small proportion of the book directly deals with that. He begins by pointing out some people's attempts to relate programs and arts

  • According to Graham, the iterative processes of programming - write, debug (discover and remove bugs, which are coding errors, mistakes), rewrite, experiment, debug, rewrite - exactly duplicate the methods of artists (p.2)
  • 'Let us change our traditional attitude to the construction of programs: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do' (Donald Knuth - literate programming)
  • "Of all the different types of people I've known, hackers and painters are amongst the most like" (Paul Graham) (p.2)

He points out that US and Indian computer cultures are different

  • In a 2013 interview, the executive chairman of Google, Eric Schmidt, said, "Forty per cent of the startups in Silicon Valley are headed by India-based entrepreneurs" (p.75)
  • This [Indian] educational process, with its obsessive emphasis on examinations and rankings, produces legions of rote learners, mark grubbers, and cheaters. It causes casualties - 7379 students committed suicide in 2010, at increate of 26 per cent over 2005 (p.77)
  • the proportion of undergraduate computer-science degrees awarded to women in the US has declined from 37 per cent in 1984 to 18 per cent in 2010 ... Meanwhile, in India, the trend has gone in the other direction ... in 2003, 32 percent of the Bachelor of Engineering degrees in computer science and 55 per cent of the Bachelor of Science degrees in computer science were awarded to women (p.80)
  • research in countries as varied as Iran, Hong Kong, Mauritius, Taiwan, and Malaysia has yielded results consistent who those found in studies in India, showing that there is nothing about the field of computing that makes it inherently male. Varma's conclusion is blunt: 'The gender imbalance in the United States seems to be specific to the country; is not a universal phenomenon (p.83)

He quotes some interesting facts about computer languages

  • COBOL .. still processes 90 per cent of the planet's financial transactions, and 75 per cent of all business data (p.128)
  • Malboge ... is so impenetrable that it took two years after the language was first released for the first working program to appear, and that program was not written by a human, but generated by a computerized search program that examined the space of all possible Malboge programs and winnowed out one possibility (p.130)
  • The open-source database SQLite, at the time of this writing, has 1177 times the amount of test code as it does program code (p.155)

He deals with Indian theories of aesthetics

  • It is the very artificiality and conventionality of the aesthetic experience, therefore, that makes the unique experience of rasa possible (p.150)
  • The speech of the poet can be effective even when it doesn't obey the rules of everyday language. According to Abhinavagupta, even the denotative and connotative meanings are only aids to the production of rasa, unessential props which can sometimes be discarded (p.155)
  • Indian movies mix emotions and formal devices in a manner quite foreign to Western filmgoers; Indian tragedies accommodate comedic scenes, and soldiers in gritty war movies can break into song ... This is why the Aristotelian unities of British and American films seemed so alien to me (p.161-2)
  • Mary Douglas writes ... 'ring composition is extremely difficult for Westerners to recognise.' ... ... When I was writing my first book, I had never heard the phrase 'ring composition,' but the method and its specific implications and techniques came readily to hand because - of course - I had seen and heard it everywhere. What I wanted within the nested circles or chakras of my novel was a mutual interaction between various elements in the structure (p.165)
  • Shulman writes that in India, reiterations and ring compositions 'speak to a notion of reality, in varying intensities and degrees of integrity, as resonance, reflection, or modular repetition understood as eruption or manifestation (avirbhava) from a deeper reservoir of existence (p.167)

Then he gets into Indian metaphysics and Tantric practices, the role of woman in Indian culture, Sanskrit and the consequences of the Empire. Finally he returns to the literature/programming issue -

  • programmers ... often seem convinced that they already know everything worth knowing about art ... to make art, you don't have to become an artist - that anyhow, is only a pose - you just analyse how art is produced, you understand its domain, and then you code art (p.209)
  • For my own part, as a fiction writer who has programmed, thinking and feeling as an artist is a state of being utterly unlike that which arises when one is coding (p.210)
  • To compare code to works of literature may point the programmer towards legibility and elegance, but it says nothing about the ability of code to materialize logic ... Most discussions of the beauty of code I have encountered emphasize formal qualities of language - simplicity, elegance, structure, flexibility ... But programs are not just algorithms as concepts or applied ideas; they are algorithms in motion. Code is unique kinetic. It acts and interacts with itself, with the world. In code, the mental and the material are one. Code moves. It changes the world (p.221)

Tuesday, 5 August 2014

"The Art of UNIX Programming"

This book's by Eric S. Raymond, published by Pearson Education. Though it dates from 2004 it's still interesting. It filled some gaps in my knowledge.


  • "There is evidence [Hatton97] that when one plots defect density versus module size, the curve is U-shaped and concave upwards" (p.86)
  • "second-system effect" - "the urge to add everything that was left out the first time around" (p.29). "third-system effect" - "after the second system has collapsed of its own weight, there is a chance to go back to simplicity and get it really right. The original Unix was a third system" [after CTSS and Multics] (p.29)
  • "Holding down the shift key required actual effort: thus the preference for lower case, and the use of "-" (rather than the perhaps more logical "+") to enable options" (p.242)
  • "marshalling" means "serialising"
  • "A program is transparent when it is possible to form a simple mental model of its behaviour that is actually predicive for all or most cases" (p.133)
  • "Software systems are discoverable when they include features that are designed to help you build in your mind a correct mental model of what they do and how they work. (p.133)
  • "Threading is a performance hack ... they do not reduce global complexity but rather increase it" (p.159)
  • "Despite occasional exceptions such as NFS and the GNOME project, attempts to import CORBA, ASN.1, and other forms of remote-procedure-call interface have largely failed - these technologies have not been naturalized into the Unix culture" (p.178)
  • "Today, RPC and the Unix attachment to text streams are converging in an interesting way, through protocols like XML-RPC and SOAP" (p.179)
  • "Unix was the first production operating system to be ported between differing processor familes" (p.393)


  • "Emacs stands for Editing MACroS" (p.351)
  • "yacc has a rather ugly interface, through exported global variables with the name prefix yy_. This is because it predates structs in C; in fact, yacc predates C itself; the first implementation was written in C's predecessor B" (p.353)
  • scp calls ssh "as a slave process, intercepting enough information from ssh's standard output to reformat the reports as an ASCII animation of a progress bar" (p.169)
  • "No discussion of make(1) would be complete without an acknowledgement that it includes one of the worst design botches in the history of Unix. The use of tab" . The author said that he "had a user population of about a dozen, most of them friends, and I didn't want to screw up my embedded base. The rest, sadly, is history"


  • "Outside of Fortran's dwindling niche in scientific and engineering computing, and excluding the vast invisible dark mass of COBOL financial applications at bank and insurance companies, C and its offspring C++ have now (in 2003) dominated applications programming almost completely for more than a decade. It may therefore seem perverse to assert that C and C++ are nowadays almost always the wrong vehicle for beginning new applications development. But it's true; C and C++ optimize for machine efficiency at the expense of increased implementation and (especially) debugging time" (p.323)
  • "C++ is anti-compact - the language's designer has admitted that he doesn't expect any one programmer to ever understand it all" (p.89)
  • "Python is "generally thought to be the least efficient and slowest of the major scripting languages, a price it pays for runtime type polymorphism" (p.337) "it encourages clean, readable code and combines accessibility with scaling up well to large projects" (p.338)


  • "The OO design concept initially proved valuable in the design of graphics systems, graphical user interfaces, and certain kinds of simulation. To the surprise and gradual disillusionment of many, it has proven difficult to demonstrate the benefits of OO outside those areas" (p.101-2)
  • "Unix programmers have always tended to be a bit more skeptical about OO than their counterparts elsewhere" (p.102)
  • "a lot of programming courses teach thick layering as a way to satisfy the Rule of Representation. In this view, having lots of classes is equated with embedding knowledge in your data. The problem with this is that too often, the 'smart data' in the glue layers is not actually about any natural entity in whatever the program is manipulating - it's just about being glue" (p.102)
  • "One reason that OO has succeeded most where it has (GUIs, simulations, graphics) may be because it's relatively difficult to get the ontology of types wrong in those domains" (p.103)

Quotes by others

  • "This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface" (Doug McIlroy)
  • "La perfection est atteinte non quand il ne reste rein à ajouter, mais quand il ne reste rien à enlever" (Antoine de Saint-Exupéry)
  • "C++: an octopus made by nailing extra legs onto a dog" (anon)
  • "Beauty is more important in computing than anywhere else in technology because software is so complicated. Beauty is the ultimate defense against complexity" (David Gelernter,"Machine Beauty: Elegance and the Heart of Technology")
  • "When in doubt, use brute force" (Ken Thompson)
  • "If you know what you're doing, three layers is enough; if you don't, even seventeen levels won't help" (Padlipsky)

Tuesday, 6 May 2014

Which computing language for engineers?

At our site we teach general engineering - students amongst other things can learn AI, Economics, and bridge-building. Which language should they be taught? Though their needs are different from those of Computing students and of more specialist (e.g. Electrical) Engineering students, their programming needs may be extensive. In Teaching Introductory Programming in Tertiary Engineering Education M.G. Rashed points out that "Computers are increasingly used for a variety of purposes in engineering and science including control, data analysis, simulations and design optimization. It is therefore becoming more important for engineering students who are computer science non-major, to have a robust understanding of computing and to learn how to program". It's over 15 years since we last changed the primary language (I've found a document from 1996 which addresses the issue - Teaching Programming in the Engineering Tripos). In that time much has changed in the world of engineering, so a review of our language choice is timely.

1985Pascal as a 1st language
1996?Matlab as a 2nd language
1997C++ as a 1st language
???Compulsory computing questions
in the 1st year exams.
2008Vacation C++ exercise
20101st week Lego Mindstorms (Matlab)
2012C++ course flipped - 25% more labs
at the expense of lectures
2014Scratch used in a prelim exercise


Firstly then, what factors could influence our choice, and how have those influences changed over the years? Here are a few -

  • The history and culture of the department - the department tends to teach the fundamentals in a non-specialist way for the first 2 years of a student's career
  • The value of programming in general - When I was taught Latin at school I was told that it was good for me, it trained my mind. Nowadays Mandarin might be taught on the grounds that it's a common language, or Esperanto because it's an easily learnt, well-designed one. Similar differences of opinion apply to the reasons for teaching computing languages. Programming skills might have intrinsic value or be widely transferable. According to its advocators, Computational Thinking "involves a set of problem-solving skills and techniques that software engineers use to write programs ... However, computational thinking is applicable to nearly any subject. Students who learn computational thinking across the curriculum begin to see a relationship between different subjects as well as between school and life outside of the classroom. Specific computational thinking techniques include: problem decomposition, pattern recognition, pattern generalization to define abstractions or models, algorithm design, and data analysis and visualization".
  • The value of programming for engineering - M.G. Rashed thinks that "The primary target in teaching computing is to enable the students to convert engineering problems into pseudo-code. ... The conversion of this pseudo-code into a program written in one programming language is of secondary importance because it is, in principle, an algorithmic procedure and requires less intellectual effort. ... In the teaching practice, the algorithmic problem- solving and implementation tasks are often entangled simply because the students need to test an algorithm they invented by implementing it. Consequently, the choice of the teaching language should be governed by which language provides the best support to the student in performing the implementation part of the problem-solving task by removing any extra stumbling blocks. For this reason the usefulness of the language after graduating or speed of execution will not be the prime factors when making the choice."
  • Requirements of other courses - some other courses assume specific aspects of computing competence.
  • Students' previous experience - A long time ago many students arrived with some programming experience thanks to home micros running BASIC and schools equipped with BBC micros. Then skills fell away. More recently, with free Linux being available, and raspberry Pi kits on sale, there's been a recovery in programming skills, but only amongst the computer literate, meaning that the distribution of our intake's computing skills is more bi-polar than ever.
  • Students' expectations -Though they may program less than earlier generations did, they use computers far more. In particular they rather expect there to be an app for everything - to supply documentation, to provide an interface to hardware (instead of a remote being provided, etc). They may hope that what they produce looks rather like an app.
  • Industry relevance - Anecdotal comments from staff suggest that some companies aren't convinced that we are preparing our students for programming. C is more useful for embedded systems than C++. Matlab experience is often requested. One problem is that the needs of industry change, and aren't easy to predict long enough in advance. The invention of the WWW and cheap, small processors has led to the use of GPS and intelligent sensors in civil engineering projects. Google Maps and Google Apps enrich projects as well as aid communication between workers. One student wrote to me that "surely as a professional chartered engineer if you need to do some programming/coding you would hire a professional who would do it in no time at all plus do it correctly" but it would be a shame if the engineer got ripped off because they hired professionals to write trivial or poorly-spec'd software.
  • Language features - ease of use, expressiveness - Despite the popularity of languages such as FORTRAN and C/C++, there has been much debate about the suitability of these languages for education, especially when introducing programming to novices. These languages have not been designed specifically for educational purpose, nor do they make for easy use of the WWW or creation of GUIs. Interpreted languages are growing in popularity (the image is from the M.G. Rashed paper).
  • Programming paradigm - Our approach emphasises the procedural aspects of C++, downplaying O-O in order to introduce more problem-solving practise.
  • Availability of compilers, IDEs, and teaching materials - We've had some trouble providing easily-installed C++ IDEs across platforms. All the teaching materials are on the WWW. Web2 technology has been exploited -
    • Documentation for the 1AC++ Mich course is now WWW-based with online PHP-based teaching aids.
    • A 2nd year C++ course went a step further, incorporating online marking.
    • The Mars Lander project uses CamTools to host documentation and student-staff communication
    Sometimes (to facilitate automated assessment for example) the presentation framework imposes limits on the nature of the course.
  • Availability of teaching staff - With class sizes of 90 or so, computing practicals require several skilled helpers.
  • Learning styles - Teaching remains based on practicals with demonstrator support. There are fewer lectures. Independent study has been encouraged by providing the MDP disc, giving help to students installing compilers on their own machines, and changing teaching material so that documentation is on the WWW, the exercises requiring the minimum of extra libraries.


One needs to assess trends with caution. Wikipedia's Measuring programming language popularity page lists, amongst others

Within education, statistics are perhaps more reliable

  • A Snapshot of Current Practices in Teaching the Introductory Programming Sequence (2011) points out that for CS0 ("an introductory course with no prerequisites, involving at least some programming, that does not count towards the major") Alice was top, though there "is a tremendous variety in approaches". In CS1 the results were: Java 48%, C++ 28%, Python 12%.
  • An InfoWorld article (2014) quotes results from an Association for Computing Machinery survey - "Eight out of the top 10 universities now use Python to introduce programming"; "Python has been growing in popularity in the educational realm for at least the past few years, though this survey is the first to show it has eclipsed Java, which has been the dominant teaching language for the past decade".
  • A Survey of Literature on the Teaching of Introductory Programming (from the ACM Special Interest Group on Computer Science Education, 2007?) gives a useful overview and annotated bibliography. It points out that
    • "Three decades of active research on the teaching of introductory programming has had a limited effect on classroom practice"
    • "Today, C, Java and C++ top the list of the most widely used programming languages, both in industry and education"
    • "Studies have found that market appeal/industry demand/student demand is one of the most important factors affecting language choice in computer science education"

Within the general trends there's significant variation - for example, Stanford have a course based on JavaScript.

Also there's an increasing use of Moocs.

Candidate languages

The SIGCSE report mentioned above says "An appropriate language can only be chosen after course goals and learning outcomes have been specified". FYI, our 2013-14 doc said

The aims of the course are to:

  • Give a good understanding of basic design methods and techniques and emphasise, in particular, the need to produce well-structured, maintainable computer software.
  • Reinforce the IA practical classes in C++ programming and provide a firm foundation for IB practical work.

As specific objectives, by the end of the course students should be able to:

  • Understand the nature of software engineering and the software life cycle
  • Appreciate the need for structured programming in software engineering projects.
  • Be able to write well-structured programs in the C++ programming language to solve practical problems.
  • Understand the sources of errors in numerical programming and how to guard against them.
  • Appreciate the issue of complexity in algorithm design, with particular reference to searching and sorting algorithms.

I think the languages below are the most commonly mentioned at CUED as options -

  • Matlab/Octave - Students use this in week 1. Only in year 2 are they more formally taught it. Matlab has a large range of material produced by univs for ugrads, much of it with a math/engg bias. In a Mathworks newsletter, staff at Vanderbilt University write that "engineers from five major companies ... credited MATLAB with helping them become more efficient and achieve time reductions 'from a week to 15 minutes' and 'from several months to weeks'" citing an automotive engineer’s statement that "MATLAB was a de facto industry standard". Many engineering-related routines and program are available.
  • Python - According to Charles Dierbach ("Journal of Computing Sciences in Colleges" 29, 6 (June 2014)), "The Python programming language has been quickly gaining popularity over the past few years as a language of choice for CS1 courses. Some estimates put the rise in use at forty-percent a year". "The Python programming language has been around since its development by Guido van Rossum around 1991. One of the main features of the language is code readability (sometimes described as "executable pseudocode"). Python is an interactive programming language, using dynamic typing. It is also a hybrid language, supporting the imperative, object-oriented and functional programming paradigms. Although used as a scripting language, it is also used for the development of full-scale programs." The University offer courses in Python for number-crunching, etc. Many engineering-related packages are available.
  • C++/Objective-C/C# - Students use C++ for about 20 hours in year 1 and at least another 8 hours in year 2. In a Cambridge university C++ course it says "Unless you are already a programmer, you are very strongly advised to learn Python first ... learning another programming language would also do. “Programmer” does not mean in Visual Basic, Excel or even most uses of Matlab; it means in Python, Fortran, C, Pascal etc. It surprises most people, but learning simpler languages first often saves time overall. ... You can learn to use any of these (even Fortran) to a comparable level in about 20% of the time that you will need to learn C++"
  • Java - one piece of 3rd year coursework currently requires students to write Java. Their C++ experience is presumed to be a sufficient prerequisite.


Are there advantages in principle in exposing students to several languages? Ultimately it's unavoidable, though perhaps initially it confuses people. We don't compare/contrast languages. We tend to leave that to the students.

Thursday, 27 March 2014

Some educational myths

Well, not myths really, but it's sometimes worth challenging cherished notions

Deep down, students know what's good for them

In "Student interest and choice in programming assignments" (Journal of computing in small colleges 26, 6 (June 2011)) Lisa Torrey surveyed 14 students to find out what motivates their choice of programming exercises. She'd hoped that students would choose programs at the optimal level of challenge but found that "students disproportionately chose to write less challenging programs than their interest patterns had suggested". She felt that "many students would choose easy programs that happen to contain other interesting factors".

In March 2014's "Assessment and Evaluation in Higher Education", Felton and Mitchell claim (providing some evidence) that "Faculty who lighten workloads and inflate grades buy high SET [Student Evaluation of Teaching] ratings and popularity for their courses". Older staff are less prone to doing this.

The more a topic's taught, the more students will learn

In "When do students learn? Investigating factors in introductory courses" (Journal of computing in small colleges, 2012) it said - "we found that instructional time spent on a topic often has a far weaker connection to student learning levels than does instructor emphasis. ... Just spending more classroom teaching time on a concept will not improve student learning as much as an instructor placing greater emphasis on that concept ... For CS1, there were few topics for which there were statistically significant correlations between instructional time and student learning".

The better the teacher's presentation, the more the students learn

In the May 2013 issue of "Psychonomic Bulletin and Review" it reported that "When a presenter is seen to handle complicated information effortlessly, students sense wrongly that they too have acquired a firm grasp of the material". They're more confident, but perform no better.

In "The Times Higher" (30/5/13, p.7) it's reported that "lecture fluency did not significantly affect the amount of information learnt".

Clarity is good

In The secret life of fluency Daniel Oppenheimer wrote that for some exercises, "participants were significantly more likely to detect the error when the question was written in a difficult-to-read font. This suggests that they were adopting a more systematic processing method and attending more carefully to the details of the question".