Use a custom implementation of promises.

Saves 43 definitions and 397 lines of (de)compiled code.

racket/src/expander/common/promise.rkt

@@ -0,0 +1,22 @@
+#lang racket/base
+
+(provide delay force)
+;; This version of promises does _not_ handle re-entrance detection,
+;; exceptions, or multiple value returns.
+
+;; val is a thunk or the eventual value
+;; status is whether the thunk has been forced already
+(struct promise (val status) #:mutable #:authentic)
+
+(define-syntax-rule (delay e) (promise (lambda () e) #f))
+
+(define (force v)
+  (cond [(promise? v)
+         (define s (promise-status v))
+         (cond [(not s)
+                (define result ((promise-val v)))
+                (set-promise-val! v result)
+                (set-promise-status! v #t)
+                result]
+               [else (promise-val v)])]
+        [else v]))

racket/src/expander/eval/module.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/promise
+(require "../common/promise.rkt"
          "../common/performance.rkt"
          "../namespace/namespace.rkt"
          "../namespace/module.rkt"

racket/src/expander/expand/context.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/promise
+(require "../common/promise.rkt"
          "../common/struct-star.rkt"
          "../syntax/syntax.rkt"
          "../syntax/scope.rkt"

racket/src/expander/expand/module.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/promise
+(require "../common/promise.rkt"
          "../common/struct-star.rkt"
          "../common/performance.rkt"
          "../syntax/syntax.rkt"

racket/src/expander/namespace/namespace.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-(require racket/promise
+(require "../common/promise.rkt"
          "../common/phase.rkt"
          "../common/small-hash.rkt"
          "../syntax/bulk-binding.rkt"