15312 Foundations Of Programming Languages link [2027]

The mid-semester project arrived: implementing a language from scratch. Alex labored over , a language that felt like writing poetry with a very angry editor.

The history of programming languages shows a shift towards abstraction. As noted by Ramotion , early attempts like Plankalkül in the 1940s aimed to move away from pure machine code.

When exactly does an argument get computed?

If a program has a type and takes a step, it still has that same type. 15312 foundations of programming languages

Many modern concurrency bugs (like data races) are solved through type systems. Rust’s ownership model, for instance, is a direct application of linear logic and substructural type systems—topics deeply rooted in language foundations. Conclusion

: Usually includes a midterm (approx. 20%) and a comprehensive final exam (approx. 25%–30%).

Teaches advanced data abstraction through signatures and structures. As noted by Ramotion , early attempts like

A deep understanding of how language features (like pointers, recursion, or polymorphism) are implemented allows you to diagnose complex bugs.

Almost every proof in this course relies on induction over the structure of expressions or derivation trees. If you master this early, the rest of the course becomes much more manageable.

A massive component of 15-312 is the study of type systems. A type system is a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute. The Static-Dynamic Dichotomy Many modern concurrency bugs (like data races) are

One of the central mantras of the course is: Type safety ensures that a program will not execute undefined behaviors (like attempting to add a string to an integer or executing random memory addresses). In 15-312, type safety is not a hand-wavy concept; it is a mathematical theorem proven using two core properties:

Writing code that works across multiple types (generics). 3. Dynamics: Execution Models

### TypeScheme

Represent "Or" logic. A sum type contains a value of type τ1tau sub 1 or a value of type τ2tau sub 2 Polymorphism and System F

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