She loves the beauty of functional programming, enjoys open and honest conversations, and is passionate about creating a more inclusive academia. After more than 30 years at Chalmers, Professor Emerita Mary Sheeran, Department of Computer Science and Engineering, can look back not only on an exciting research career, but also on decisive contributions to Chalmers’ work on gender equality.
Mary Sheeran is the engineer who stumbled into the world of research and discovered that it was far too interesting to leave. As a future Master of Engineering student at Trinity College Dublin, she wanted to combine electronics with theoretical computer science and was told that her wishes were so unusual that no one had encountered them before. But the combination was perfect for Mary Sheeran, and when in the early 1980s she was offered a doctorate at the University of Oxford, she let go of the idea of a job in industry.
Already then, she had found the area that has shaped her research ever since: functional programming in the design and verification of hardware.
Her research is particularly focused on domain-specific programming languages, not general but designed for a specific purpose – a bit like a knitting pattern. In computer science, such languages can be used to prove that hardware works as it should.
“Errors in software can often be fixed later with updates, but for hardware the requirements are strict that everything must be correct from the start. One example of what can happen otherwise is Intel’s ‘FDIV bug’ from 1994, which cost the company nearly 500 million dollars,” she says.
A pioneer who loves simplicity
Ireland-born Mary Sheeran and her husband John Hughes both came to Chalmers as postdocs in 1984, and the couple returned in 1992 after some years in Glasgow. She enjoys both the university and life in Sweden.
“In Sweden we have been able to offer our son, who has a disability, a good life. And Chalmers has always provided strong collegiality and fine support for me, especially when I was completely new,” she says.
Mary Sheeran is a pioneer in her field and is lead author of several widely cited papers. Particularly noted were her publications on proof by induction and so-called SAT solvers, which marked important steps forward in the field. She sees elegance and beauty in functional programming, which she believes has value in itself.
“I love simplicity, and people in functional programming often see something beautiful in being able to present functions in a clear way. It feels a bit like showing an expressive photograph,” she says.
Much has happened in the field since she studied for her engineering degree in the late 1970s, especially with the arrival of AI.
“AI is exciting and really paves the way for new opportunities at the intersections of different subjects. But this requires more and better collaboration between engineers and scientists. And these collaborations must include different people with different experiences and approaches to the challenges that AI places before us,” she says.
Honest conversations are needed
Here Mary Sheeran touches on a general problem she sees: that blinkers and territorial thinking characterise behaviour within academia. Something she feels affects the working climate and limits collaborations.
“I see this in many contexts at Chalmers, everywhere and at all levels. There is a very limited view of what is most important to focus on, and those who want to take a broader approach, or have a different perspective, risk being excluded. I think we need open and honest conversations to bring about a cultural change, where we truly dare to talk about the system we are part of and what needs to change,” she says.
Mary Sheeran is deeply engaged in gender equality issues at Chalmers, work for which she has also been recognised with an award. Some years ago, both she and Chemistry Professor Pernilla Wittung Stafshede – without knowing of each other’s initiatives – wrote proposals for a strong focus on gender equality, in response to management’s call for ideas on how Chalmers could improve. This became the seed of Chalmers’ ten-year, 300-million SEK initiative Genie, with the aim of improving the university’s gender balance and creating a more inclusive working environment.
“I have long been the only female professor at my department. That brings many challenges, and being ‘unusual’ as a woman also means that you always represent your gender, in addition to your research. But what really made me react was when I realised that only twelve percent of the department’s first-year students were women. When I was a student in Dublin in 1976, we were ten percent women. It is incredible that not more has changed in almost 50 years,” she says.
Equality on the agenda – but much remains
She describes her involvement in Genie as exciting, fascinating – and difficult.
“Working with gender equality means working with incredibly complex issues. It is actually much more complicated than any research I have dealt with. It is not easy to achieve change in systems that are influenced by how society is structured, hierarchical structures where in many places there is a lack of willingness to change, and not least 13 different departments all working in different ways,” she says.
She is pleased that Genie has put gender equality on the agenda and feels that the resistance the initiative faced in the beginning has diminished. Above all, she is proud of the changed recruitment processes that have, among other things, led to gender distribution among Chalmers’ assistant professors now being around 50/50. But much remains to be done, she points out.
“We need to be more open, more willing to bring new and differently thinking people into our groups. And we need to work on cultural change within the faculty: everyone needs to reflect on what we can do to create a more inclusive environment. In addition, gender equality efforts need to be more clearly rewarded, and visible in the pay packet.”
As emerita she plans to keep in touch with colleagues and continue with some research. But she will also have more time for her leisure interests.
“I play table tennis in a training group for women at Askim’s table tennis club and have also dared to join the ‘seniors’: a group of pleasant and table-tennis-mad pensioners, almost all men. It is great fun! I also enjoy walking in the forest and photographing trees, stones, moss and lichens. I look forward to being able to spend more time on that,” she says.
Text: Ulrika Ernström
More about Mary Sheeran
Title: Professor (from 1 March 2025 Emerita) in functional programming at the Department of Computer Science and Engineering, Chalmers University of Technology
Born: Dublin, 1959
Family: husband (John Hughes, also Emeritus at Chalmers) and two sons
Leisure interests: photography, table tennis
Role model: John Backus, American computer scientist and Turing Award winner. “My doctoral thesis was based on his research. To my horror he was in the audience when I gave my first, nervous, conference presentation on that work in Austin, Texas in 1984. He came up to me after the talk and said that it was the nicest use of functional programming he had ever seen. I loved that he took the time to talk to a young researcher in that way. We need more people who behave like Backus – kind, open and curious!”
Mary Sheeran on…
…the significance of Genie:
“The cost of failing with gender equality work is high. We need female researchers and engineers to change the world. In addition, young people today are more aware of the importance of gender equality. I know several young researchers who say that Genie was an important reason why they applied to Chalmers.”
…exciting periods in her career:
“Around the turn of the millennium Gunnar Stålmarck worked at Chalmers, entrepreneur and adjunct professor in applied computer science. We found exciting collaborations and for a few years I combined research with working in his company. It was an experience that gave a lot, above all by giving me new ways of looking at research.”
…how life as a researcher has changed:
“I perceive that research life is tougher today than when I started. The time pressure is tangible, and there is greater competition for the funding opportunities available. In addition, grants have become fewer and smaller in scope.”
…advice to young researchers:
“Work on your writing, both in your articles and in applications. Your research is not good research until you have managed to write about it well. And take the help that is available, for example if you are applying for funding.”
Longer explanation of the pictures of sorting networks:
Mary Sheeran: "The programs are very small, and easy to read for someone familiar with the language. They are like good knitting patterns!"
The first picture illustrates a sorting network. Inputs flow in on the left and along the horizontal wires. The vertical lines are comparators that output the maximum on the top and the minimum on the bottom. This is a 64 input instance of Parberry's pairwise sorting network. Its recursive structure is captured in the function pwSort. What happens if we only need the K largest inputs?
The second picture on the right shows a network that produces the top 8 inputs in order on the topmost 8 wires. It was found by programmatically dropping some comparators from the sorting network. It was proved correct using a SAT solver. Examining the generated diagrams for different sizes allowed it to be programmed directly in the function pwSel. This network is the same size as the best known, and simpler to describe. Having a language to describe these regular and almost regular structures and ways to visualise and prove properties of them enables understanding and innovation. Top K select is an important function in AI pipelines.
The last picture shows the code describing these algorithms.