X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=week1.mdwn;h=36ebdfcc6a48bf72288e2023a0186b9c6665de2d;hp=5ae3e65f5c154f36a84432585178ed81bdb179ba;hb=00b6e7be50487a25a1d96ec239f04271f0be53a6;hpb=9452f39dcc5b7babde45142e2b24e3617813d6a6
diff --git a/week1.mdwn b/week1.mdwn
index 5ae3e65f..36ebdfcc 100644
--- a/week1.mdwn
+++ b/week1.mdwn
@@ -39,6 +39,24 @@ Basics of Lambda Calculus
The lambda calculus we'll be focusing on for the first part of the course has no types. (Some prefer to say it instead has a single type---but if you say that, you have to say that functions from this type to this type also belong to this type. Which is weird.)
+Here is its syntax:
+
+
+Variables: x, y, z...
+
+
+Each variable is an expression. For any expressions M and N and variable a, the following are also expressions:
+
+
+Abstract: (λa M)
+
+
+We'll tend to write (λa M) as just `(\a M)`, so we don't have to write out the markup code for the λ. You can yourself write (λa M) or `(\a M)` or `(lambda a M)`.
+
+
+Application: (M N)
+
+
Some authors reserve the term "term" for just variables and abstracts. We'll probably just say "term" and "expression" indiscriminately for expressions of any of these three forms.
Examples of expressions: