cs-4400-sp26

Lecture 1: CalcLang

Code:

• Plait demo
• CalcLang

Lecture outline

• Programming in Plait
  • Built-in types, data, functions, definitions
  • Datatype definitions
  • Type-case
• Intro to defining programming languages
  • Syntax
    • BNF grammars
    • S-expressions
    • Plait datatypes
  • Operational semantics
  • A definitional interpreter
    • Adding strings
    • Operator overloading
• Discussion
  • Meta-languages and object languages

Exercises/TPS

1. Where are some places that ambiguity shows up in surface syntax?
2. Write the AST for the expression ((2+1) * 3)
3. Write Plait defns of type CalcLang to represent
   1. 1 + 2
   2. (2 + 1) * 3
4. How could we extend the language with strings? (write new datatype and example term)

Bibliography

• Reynolds, John (1998). Definitional Interpreters for Higher-Order Programming Languages. https://homepages.inf.ed.ac.uk/wadler/papers/papers-we-love/reynolds-definitional-interpreters-1998.pdf
• Landin, Peter J. (1965). The Next 700 Programming Languages. https://homepages.inf.ed.ac.uk/wadler/papers/papers-we-love/landin-next-700.pdf
• McCarthy, John (1963). A Basis for a Mathematical Theory of Computation. https://www-formal.stanford.edu/jmc/basis1.pdf