From aa057408b5ae36d7e78e557294570b01c02cdf87 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Tue, 24 Jan 2023 21:59:22 -0500
Subject: Update some comments.

---
 chickadee/graphics/seagull.scm | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/chickadee/graphics/seagull.scm b/chickadee/graphics/seagull.scm
index 9f5aaeb..278ca63 100644
--- a/chickadee/graphics/seagull.scm
+++ b/chickadee/graphics/seagull.scm
@@ -681,13 +681,11 @@
 ;;; Typed expressions
 ;;;
 
-;; Transform all program expressions into typed expressions by
-;; applying a variant of the Hindley-Milner type inference algorithm.
-;; GLSL is a statically typed language, but thanks to type inference
-;; Seagull code doesn't need type annotations.
-;;
-;; This section includes all the kinds of types an expression may have
-;; and various transformation procedures to manipulate them.
+;; Typed expressions combine a Seagull expression with the data types
+;; that expression returns.  This section includes all the kinds of
+;; types an expression may have and various transformation procedures
+;; to manipulate them.  This will be used below to convert the mostly
+;; untyped Seagull program into a fully typed one.
 
 ;; Primitive types:
 (define (primitive-type name)
@@ -1051,7 +1049,9 @@
 ;;;
 
 ;; Convert untyped Seagull expressions into typed expressions with
-;; variable components that need to be solved for.
+;; type variables representing all unknown types.  This annotated
+;; version of a Seagull program can then be passed to the type
+;; inference algorithm to solve for all of the variables.
 
 (define (lookup-type name env)
   (let ((type (lookup name env)))
@@ -1230,7 +1230,10 @@
 ;;;
 
 ;; Walk the expression tree of a type annotated program and solve for
-;; the type variables present.
+;; all of the type variables using a variant of the Hindley-Milner
+;; type inference algorithm.  GLSL is a statically typed language, but
+;; thanks to type inference the user doesn't have to specify any types
+;; expect for shader inputs, outputs, and uniforms.
 
 (define (compose-substitutions a b)
   (define b*
@@ -1523,7 +1526,7 @@
 ;;; GLSL emission
 ;;;
 
-;; Transform typed expressions into a string of GLSL code.
+;; Transform a fully typed Seagull program into a string of GLSL code.
 
 (define (type-name type)
   (primitive-type-name type))
-- 
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