Amend README

1 files changed, 22 insertions, 0 deletions

diff --git a/README.md b/README.md
index 3cfddcb..37ea5ae 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,25 @@
 * SimpleShell compiles to POSIX sh, where the output is supposed to be
   human-readable.
 * The syntax is de facto a mixture of sh, C and Haskell.
+
+
+## Variables
+
+* Variables are local to their function or procedure; there are no (nested)
+  variable scopes.
+* All variables have static types.  Same for function and procedure
+  signatures.
+
+
+## Functions
+
+* Functions are pure; they compute a single value from a list of arguments.
+* Compare pure Haskell functions.
+
+
+## Procedures
+
+* Procedures are similar to POSIX sh functions.
+* Procedures take a list of arguments, and return a pair of
+  exit code and return value.
+* Procedures may receive data from stdin and write data to stdout and stderr.