Class 15: Scheme Semantics (1)

Held Friday, February 26

Summary

• Assignment 3 distributed.

Contents

Handouts

• Assignment 3: Denotational Semantics

Notes

• I've updated the syllabus. I've dropped the section on Haskell (which would have been your third functional language) and added a guest-lecture by Dr. Walker for next Wednesday.
  • I'll be at a ``master planning'' meeting on technology on campus.
• The Math/CS SEPC is hosting a study break next Monday at 7:30. You are encouraged to attend.

The Semantics of Scheme

• Notation on p. 40 is important. Make sure you understand it.
• Abstract syntax is fairly straightforward.
• Domain equations begin to get more complex.
• Semantic functions are the interesting ones.

Terminology

• What are injection and projection?
• They are a lot like type casting.
  • One is like casting from a superset/supertype to a subset/suptype (X is declared as an Object, but we know that it's really a Number, so we call it a number).
  • One is like casting from a subset/subtype to a superset/suptype (X is declared as an integer, but I want to treat it as a real).

Example

• What is the meaning of the equation using ``new'' near the bottom of column 2 of p. 40?

Typography

• Capital Greek letters are used for ______
  • I'll try to use italic uppercase in the web page
• Three-letter combinations are used for ______
• Multi-letter typewriter face is used for ______
• Single-letter typewriter face is used for ______
• Lowercase Greek letters are used for ______
  • I'll try to use italic lowercase in the web page
• Italicized Roman words are used for ______
• Capital script letters are used for ______
  • I'll try to use bold in the web page

History

• Created Tuesday, January 19, 1999 as a blank outline.
• Filled in the details on Thursday, February 25, 1999. (Taken from the previous outline.)
• Removed some uncovered stuff (and added some covered stuff) on Sunday, February 28, 1999.