Mix-in Steve

I would never have guessed that my research in programming languages would take me to the last remaining location of a hipster Massachusetts ice cream parlor established in the ’70s. I would never have guessed that the first dot-com domain ever registered had any relation to the invention of cookies-and-cream ice cream. If you will bear with me through tangents about MIT, Lisp, hippies, New England scoop shops, and a tech startup—here’s the story.

Steve Herrell grew up making ice cream in his backyard in Washington, D.C. every summer. Then he went to college (UMD College Park class of 1967), conscientiously objected to serving in the war, moved to Cambridge, Mass. to fulfill his alternative assignment as a high-school English teacher, and had a brief stint as a cab driver. I imagine he viewed all this as but a distraction from what he knew and loved best: ice cream. Living in a group house near Porter Sq., Herrell tinkered with a mechanical ice cream maker and fed his friends experimental ice cream. (Having myself lived in a group house of twenty-somethings not far from Porter Sq., I think I can imagine what this was like. I’ve certainly tried my share of experimental food, and ‘food’, made by housemates who were the modern counterparts of conscientious objectors.) When Herrell was sufficiently satisfied with the results, he opened Steve’s Ice Cream in neighboring Somerville, Mass. in 1973.

Steve Herrell posing with one of his custom ice cream machines inside Steve’s Ice Cream in 1973.
Steve Herrell in 1973. Source:

A short walk away was the MIT Artifical Intelligence Laboratory, the precursor of today’s CSAIL. The AI Lab is hallowed ground for someone like me. Not only because I would start my own academic career at CSAIL a few decades later, but also because that’s where the foundations were laid for the programming languages research I do now. Right around when Herrell was experimenting with ice cream, engineers at the AI Lab were discovering (inventing?) the most fertile soil for this research field: Lisp. Lisp was a family of languages with a simple yet mathematically precise core that could be fully explained in just a few pages or half an hour at a blackboard. Building on this, dialects of Lisp proliferated, pioneering concepts that are now so fundamental that programmers can’t imagine a usable modern language without them. But for some engineers, Lisp was more than just a way to program. Lisp was a way of life. Beyond computing in Lisp, they were convinced that the path to global salvation lay in computing on Lisp, i.e. doing all their everyday work on a computer system that was built with Lisp, on top of hardware devoted to executing Lisp instructions. Thus work started on “Lisp machines” in the mid-1970s, involving among many others, engineers named Dan Weinreb and Howard Cannon.

Meanwhile, Herrell’s way of life was reflected in his original independent hipster ice cream parlor. A 1983 editorial in The Washington Post describes its vibe very well: “[Herrell] dragged in a player piano that ran on a vacuum cleaner motor, left boxes lying around, painted the place in bright colors, stood around cracking jokes and started a revolution.” Or in fewer words, from Gus Rancatore: “The look was improvised hippie tree house.” (Rancatore and his sister Mimi Rancatore cleaned the floors at Steve’s, learned to make ice cream as a side effect, and went on to open Toscanini’s, MIT’s best-loved ice cream shop today. As someone who’s been to Toscanini’s many times without knowing this bit of history, I find this absolutely wild. More details are surely to be found in Gus Rancatore’s 2006 memoir, Ice Cream Man: 25 Years at Toscanini’s.) The hipster aesthetic is unsurprising given Herrell’s CO leanings and Cambridge group house membership. Indeed, the hippie vapors in the air permeated almost everything of that period, including Lisp. As Dan Weinreb puts it: “[B]ack then we really believed in Lisp. […] We really did think Lisp would ‘change the world’ analogously to the way ‘sixties-era’ people thought the world could be changed by ‘peace, love, and joy’.”

But Herrell’s real revolution was blended deep into his ice cream, moments before it was sold. He called them “mix-ins”. Ordinary though it sounds to us today, Herrell was the first to let customers choose bits of candy, cookies, fruits, and more to have mixed in with base ice cream flavors (often themselves innovative and unusual). His skill with a spatula and the rich, fresh ice cream from his custom machines made the toppings feel less like ‘toppings’ and more like they’d been in there all along. The term “mix-ins” was in use since at least 1975, when Steve’s and their mix-ins were featured in The Boston Phoenix’s Guide to Cheap Eats. Herrell stakes a plausible claim to the invention of cookies and cream as an original mix-in at Steve’s.

In parallel, a revolutionary idea was being realized at the MIT AI Lab. Howard Cannon was working on an object-oriented extension to Lisp for Lisp machines. Object-oriented programming was nothing novel on its own. It’s a style of programming in which you can define a class, such as “Dog”, that specifies properties and actions common to all dogs; then, you can create objects of the class Dog representing individual instances of dogs, that can perform the actions specified in the class (such as chasing an object of class Cat). Creation and interaction of objects makes up the whole computer program. But notice that dogs and cats are both mammals, and share some properties common to all mammals, such as giving birth to live offspring. So we can define a class Mammal with that property and make both Dog and Cat inherit from Mammal such that any object of Dog or Cat inherits the properties of Mammal too.

What was novel in Cannon’s work was how it handled multiple inheritance, a fundamental problem of object-oriented programming. In our example, just as dogs and cats are both mammals, they’re both pets, too, so they also inherit from a class Pet. And say, for the sake of example, that a property common to all pets is that they don’t give birth at all because they’re required to be spayed. But we have a problem—mammals are supposed to give birth to live offspring! Does an object of class Dog give birth, or not? There’s nothing in our definitions that tells us whether Mammal or Pet takes priority, and we can’t neatly ‘order’ them, because not all pets are mammals nor vice versa. Cannon’s system was the first to offer a satisfactory resolution for multiple inheritance. It let programmers combine different classes, such as Mammal and Pet, without necessarily imposing a hierarchy among them, and gave programmers a systematic way to specify how conflicting definitions from different classes of the same property should be combined (or prioritized) when creating an object.

A screenshot of the graphical user interface of a 3D modeling program on a Lisp machine.
Howard Cannon’s programming language would later enable a powerful graphical user interface on Lisp machines. Source: Rainer Joswig,

This was hard work, of course, and computer engineers love an ice cream break just as much as anybody else. I decided to ask Gerry Sussman if he had any stories to share. Sussman was a contemporary of Weinreb, Cannon, et al. at the AI Lab, working on a Lisp dialect called Scheme while the latter worked on Lisp machines. He went on to become a professor at MIT, where I had the pleasure and privilege of taking his symbolic systems class, full of stories about Scheme, Lisp machines, and more. He wrote to me that the engineers at the MIT AI Lab “certainly often went to Steve’s to get ice cream”. But while he remembered his colleagues, he said he had lost track of Cannon over the years, which meant it was up to me to track him down if I wanted personal stories. No matter; I’m a native child of the Internet. But Cannon wasn’t, and I doubted whether my email to an address I had found online would even reach him.

So I consider his next-day reply a miracle. “I remember thinking that like mixing together various flavors, sometimes the combinations [of classes] worked and sometimes they didn’t. [Steve’s’] ‘mixins’ seemed very analogous to starting out with a ‘base’ class and then adding in other behaviors that complemented the base.” With this useful metaphor in mind for talking about his innovations, Cannon decided to call his programming language “Flavors”. And the key idea behind non-hierarchical composition of classes? “Mixins”. That was it! Herrell, via Cannon, MIT, and ice cream creativity, made a mark in the history of programming languages of a scale that most computer scientists can only aspire to.

Cannon added that Steve’s wasn’t even the only hippie upstart New England ice cream influence on MIT Lispers, as ridiculously specific as that sounds. Nearby Emack & Bolio’s, founded in 1975 by self-described “hippie lawyers working pro bono for the homeless, for gay civil rights, for anti-war demonstrators and […] famous rock ’n rollers who were being signed by major record labels”, directly inspired the name of Dan Weinreb’s text formatter for Lisp machines, “Bolio”. “[It] made punny sense given that Emacs [a popular Lisp-based text editor] and Bolio were used together—Emacs to write the markup text and Bolio to process it into formatted output.”

Both types of mixins had strangely similar fates from the moment of their creation. Cannon’s mixins, in one form or another, were adopted by many programming languages to great success. Some examples that remain in the mainstream today are Java’s interfaces with default methods, TypeScript’s mixins, traits in Scala and Rust, and programming patterns in many other languages (often dynamic ones like Python and JavaScript) that emulate mixin behavior even if it isn’t directly a feature of the language. (An unsubstantiated side note about the origin of the term is what led me down this rabbithole in the first place while studying Scala’s mixin traits.) Cannon, along with Weinreb and others, went on to found Symbolics, Inc. to sell complete Lisp machines for personal and business computing. The Flavors programming language was a central component of the window system on these machines, which let a user interact with multiple applications in different windows on the same screen, and provided common display utilities to those applications.

Herrell’s mix-ins were no less influential. The Encyclopedia of American Food & Drink described it rather blandly in 1999—“[mix-ins] became very popular in the 1980s in the new ice cream shops opening in towns and suburban shopping malls”—but Rancatore, again from his vantage point at Toscanini’s, could expand on that with substantially more emotion, ten years later. “Every college town in America soon had a pretty good ‘homemade’ ice cream store. A hundred flowers bloomed and Americans could get a dizzying variety of flavors, complete with mixed in candy bars, fruits and nuts. A few years ago Steve’s original ideas became the basis of several boring chains, including Marble Slab and Cold Stone Creamery. Steve’s ‘small is beautiful’ ideals were heaved into the Dumpster behind a thousand strip malls.” Although he doesn’t name them explicitly, it’s not hard to guess Rancatore’s opinion of the two enterprising Vermonters named Ben and Jerry who “copied [Steve’s] down to the player piano that was against the back wall.”

Cannon &co.’s Symbolics, Inc. didn’t make it very far, though. Weinreb lists a number of reasons in a 2007 blog post, including the almost fanatical culture at Symbolics that refused to adapt to the changing technological world around it, and the classic engineering-driven neglect of marketing and management. But he also says: “It brings back a lot of old memories for me. If you ever want to start a company, you can learn a lot from reading ‘war stories’ like the ones [about AI startups]. […] Symbolics was tremendously fun. We had a lot of success for a while, and went public. My colleagues were some of the [most] skilled and likable technical people you could ever hope to work with. I learned a lot from them. I wouldn’t have missed it for the world.” And even if Symbolics, Inc. didn’t revolutionize the tech world with Lisp machines, it left certainly its mark. On March 15, 1985, was registered as the first dot-com domain on the Internet. (It’s still up today, albeit owned by a rich tech-entrepreneur type… I’m sure there’s a moral lesson to be drawn there.)

A promotional image with three Symbolics machines and two monitors on a desk.
Symbolics machines, 1986. Source: Ralf Möller,

Business didn’t like Cannon, whereas it was Herrell who didn’t like business. Tired by success, he sold Steve’s (along with the rights to the term “mix-in”) to Joey and Nino Crugnale in 1977 for $80,000. They expanded rapidly and sold it again for $4,500,000 in 1983. Meanwhile, Joey Crugnale had opened the first Bertucci’s pizza restaurant two doors down from a Steve’s, to prevent any ice cream competitors moving in. Bertucci’s is now a national chain and almost as well-known at MIT as Toscanini’s, but assuredly less beloved. (The majority of Bertucci’s an MIT student eats is in the form of free pizza at talks and events.)

Herrell seems to have had no concrete plans for what he would do after selling Steve’s, so the following few years were as colorful as the man himself. One source says he dreamed of “taking a cabin in the Berkshires”; another says he wanted to raise goats; a third mentions only “the vague intention of ‘homesteading’”; a fourth relates that he had taken up tap dancing, because it was “good exercise and develops showmanship and confidence”. What he actually did was tune pianos in Northampton, Mass. until the three-year non-compete clause of his sale agreement expired, and opened Herrell’s Ice Cream in 1980. “Used to be called Steve Herrell’s, but the Crugnales sued him for using his own first name.” Of course, “mix-ins” were trademarked, too, so he called them “smoosh-ins”. (What if modern programming languages had “smoosh-ins” instead?) Herrell started dating Judy Udes in 1983, who soon became Judy Herrell, and played an active part in the development of Herrell’s from then onwards. The brand had expanded back into Boston by 1985. A lot had changed, but in a way, nothing had.

In fact, the Allston, Mass. location that opened in 1984 was perhaps truest to Herrell’s character. “Other stores have a blue-and-white color scheme. In Allston, the walls are lemon-yellow and hung with local art. Other locations play light pop; this one blasts punk rock. The official Herrell’s logo: two teddy bears sharing a sundae. The Allston Herrell’s logo, now defunct: an ice cream cone shaped like a skull. […] [A] pirate radio station broadcast out of the back room. Rock musicians, bike messengers, and local characters showed up for coffee and stayed all day.” The Boston Globe further describes the proprietors, Page Masse and Derek Brown, as “a short, cheerful woman embellished with tattoos” and “her husband [who] was playing in a punk band whose name cannot be printed in a family newspaper”. This Herrell’s franchise brought a little independent flavor to Allston alongside excellent ice cream, until Steve and Judy Herrell split the management of the Northampton location and other franchises between themselves in 2008. (The couple had amicably divorced in 2000.) Following disagreements with Judy Herrell in 2009, the Allston franchise disaffiliated and rebranded as Allston Cafe, “rather than tone down the decor and have staff wear pastel T-shirts with teddy bears”. Rising rents forced Allston Cafe to close in 2010. Again, I’m sure there’s a moral lesson to be drawn there.

Nevertheless, the ‘original’ Northampton location is still going strong today. Steve Herrell himself made the occasional appearance at the store until he retired just a few years ago (he is 78 today). He published his memoir, Ice Cream and Me, just last year, nearly fifty years after Steve’s Ice Cream first opened its doors in Somerville. I wonder if it contains any mention of his unwitting impact on programming languages.

Smoosh-ins being smooshed into ice cream with two spatulas.
Smoosh-ins in action at Herrell’s in Northampton, Mass.

As for me, I took the opportunity while I was in Cambridge for a couple weeks in January to do the 90-minute drive to Northampton. The Herrell’s shop was nondescript but had a steady stream of customers, as befits a New England scoop shop on a mid-winter evening. There were plenty of cutesy teddy bears and pastel colors; I internally winced a little on behalf of Allston Cafe. There was a brief snafu with a new employee who didn’t know that she wasn’t supposed to mix my choice of mix-ins into two flavors of ice cream, which is what I had asked for, and which she had started doing, because both she and I believed it was a sensible request. No, the other employee said, you have to throw it out, do it again with only one flavor. Throw it out! Only one flavor! I felt something about the quintessential childlike joy of ice cream had been lost. Nevertheless, I got to watch my amended mix-ins (or rather, smoosh-ins) order be skillfully executed, spatulas and all. In the end, the walnuts and Heath Bar pieces bore testament to the legacy of Steve Herrell, because they tasted like they’d been inside the malted vanilla ice cream all along.

– Shardul Chiplunkar
20 Feb. 2023


“A photo history of Herrell’s ice cream”. The Boston Globe. Archived from the original on 19 Jan. 2019.

“Allston Cafe closes its doors”. The Boston Globe, 12 Nov. 2010. Archived from the original on 8 Aug. 2022.

Bapopik at AOL.COM. “Mix-Ins (Steve’s ice cream, Boston, 1975)”. American Dialect Society mailing list, hosted at LinguistList, 3 Aug. 2002. Archived from the original on 8 Dec. 2022.

Brown, Sasha. “Ice cream maker still sweet on MIT”. MIT News, 4 Jan. 2007. Archived from the original on 2 Jul. 2022.

Cannon, Howard I. “Flavors programming language & Steve’s Ice Cream”. Personal correspondance, 19 Dec. 2022.

Cannon, Howard I. “Flavors: A non-hierarchical approach to object-oriented programming”. 1979, updated 1992, 2003, 2007. Archived from copy at Software Preservation Group, Computer History Museum, on 12 Aug. 2022.

Covell, Jeffrey L. and Christina M. Stansell. “Bertucci’s Corporation”. International Directory of Company Histories, vol. 64, pp. 51–54, ed. Tina Grant. St. James Press, London, 2005. Accessed online.

Fieldman, Luis. “‘Chaotically ambitious’: Herrell’s owner takes life two scoops at a time”. Daily Hampshire Gazette, 9 Aug. 2019. Archived from the original on 5 Jan. 2022.

Gladstone, Brooke. “Ice Cream Wars: The Terrible Swift Umlaut”. The Washington Post, 24 Jul. 1983, p. C1. Archived from copy at Herrell’s Ice Cream & Bakery on 22 Jun. 2019.

Joswig, Rainer. “Symbolics User Interface Examples”. Archived from the original on 16 Dec. 2020.

Kinney, Jim. “‘I’m kind of a vanilla guy’: Steve Herrell shares confessions and memories in his new book, ‘Ice Cream and Me’”. MassLive, 3 Jan. 2022. Archived from the original on 3 Jan. 2022.

Levin, Sala. “From the Mixed-in Files of Mr. Ice Cream”. Terp, University of Maryland, 2018. Archived from the original on 30 Aug. 2022.

Mariani, John F. “Ice cream”. The Encyclopedia of American Food & Drink, p. 166. Lebhar-Friedman Books, New York, 1999. Accessed online.

Meystedt, Aron. Archived from the original on 18 Dec. 2022.

Möller, Ralf. “Symbolics Lisp Machine Museum”. Archived from the original on 19 Sep. 2020.

“Our Company Legacy”. Herrell’s Ice Cream & Bakery. Archived from the original on 27 Mar. 2022.

“Our Story”. Emack & Bolio’s. Archived from the original on 15 Dec. 2022.

Rancatore, Gus. “R.I.P. Herrell’s Ice Cream: A toast from Toscanini’s”. Cambridge Day, 18 Sep. 2009. Archived from the original on 10 Aug. 2022.

Rosenbaum, S. I. “Punk rock creamery takes stand”. The Boston Globe, 23 Jun. 2009. Archived from the original on 20 Mar. 2022.

Silver, Paul A. The Boston Phoenix’s Guide to Cheap Eats, 3rd ed. Harvard Student Agencies, Cambridge, MA, 1975. Quoted in Bapopik.

Starr, Mark. “I Scream, You Scream”. Newsweek, 2 Jan. 1989. Archived from copy at Herrell’s Ice Cream & Bakery on 14 Dec. 2016.

“Steve Herrell’s legacy of slow churned ice cream lives on in Massachusetts”. WCVB, 10 Jun. 2021. Archived from the original on 21 Jun. 2021.

Sussman, Gerald J. “Flavors programming language & Steve’s Ice Cream”. Personal correspondance, 9 Dec. 2022.

Weinreb, Daniel L. “Why Did Symbolics Fail?”. Dan Weinreb’s Blog, 16 Nov. 2007. Archived from the original on 14 Mar. 2013.

“Whois Record for”. DomainTools. Accessed online on 18 Dec. 2022.