From 75206940a98f7487da8a0398ab5de12fbafe3a71 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sat, 7 Jan 2023 09:08:19 -0500
Subject: Add begin form.

---
 infer2.scm | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/infer2.scm b/infer2.scm
index 569792d..18f8ef2 100644
--- a/infer2.scm
+++ b/infer2.scm
@@ -147,6 +147,12 @@
   (make-texp (texp-types body*)
              `(let ,(map list vars vals*) ,body*)))
 
+(define-matcher (annotate:begin ('begin exps ... last) env)
+  (define last* (annotate-exp last env))
+  (make-texp (texp-types last*)
+             `(begin ,@(map (lambda (exp) (annotate-exp exp env)) exps)
+                     ,last*)))
+
 (define-matcher (annotate:lambda ('lambda ((? symbol? args) ...) body) env)
   (define parameter-types (map (lambda (_name) (fresh-type-variable)) args))
   (define env* (append (map cons args parameter-types) env))
@@ -171,6 +177,7 @@
                     annotate:if
                     annotate:values
                     annotate:let
+                    annotate:begin
                     annotate:lambda
                     annotate:call))
 
@@ -218,6 +225,10 @@
   (append (program-constraints body)
           (append-map program-constraints vals)))
 
+(define-matcher (constrain:begin ((? type? types) ...)
+                                 ('begin (? texp? texps) ...))
+  (append-map program-constraints texps))
+
 (define-matcher (constrain:lambda ((? procedure-type? type))
                                   ('lambda ((? symbol? args) ...)
                                     (? texp? body)))
@@ -237,6 +248,7 @@
   (compose-matchers constrain:if
                     constrain:values
                     constrain:let
+                    constrain:begin
                     constrain:lambda
                     constrain:call
                     constrain:other))
-- 
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