From b3c746276a940c39fe4be32a906fd4aceda5a60b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Georges=20Dup=C3=A9ron?= <georges.duperon@gmail.com>
Date: Wed, 18 Nov 2015 20:08:08 +0100
Subject: [PATCH] Used ~a instead of string-append, to concatenate long lines.

---
 graph/graph/graph2.lp2.rkt                | 20 +++++++++++++++++++-
 graph/graph/queue.lp2.rkt                 |  9 +++++----
 graph/graph/rewrite-type.lp2.rkt          |  5 +++--
 graph/type-expander/type-expander.lp2.rkt | 14 +++++++-------
 4 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/graph/graph/graph2.lp2.rkt b/graph/graph/graph2.lp2.rkt
index a908ed6..29d744a 100644
--- a/graph/graph/graph2.lp2.rkt
+++ b/graph/graph/graph2.lp2.rkt
@@ -295,7 +295,7 @@ The code above needs some identifiers derived from @tc[mapping] names:
 
 @subsection{Making with-promises nodes}
 
-We derive the @tc[with-promises] type from each @emph{ideal} node type, using
+We derive the @tc[with-promises] type from each @emph{ideal} node type using
 the @tc[tmpl-replace-in-type] template metafunction from the rewrite-type
 library. We replace all occurrences of a @tc[node] name with a @tc[Promise] for
 that node's @tc[with-promises] type.
@@ -311,6 +311,24 @@ that node's @tc[with-promises] type.
        (define-temp-ids "~a/make-with-promises" (node ...))
        (define-temp-ids "~a/with-promises-type" (node ...))]
 
+@subsection{Making incomplete nodes}
+
+We derive the @tc[incomplete] type from each @emph{ideal} node type using
+the @tc[tmpl-replace-in-type] template metafunction from the rewrite-type
+library. We replace all occurrences of a @tc[node] name with a union of the
+node's @tc[incomplete] type, and all compatible @tc[placeholder] types.
+
+@; TODO: use a type-expander here, instead of a template metafunction.
+
+@CHUNK[<define-with-promises>
+       (define-type node/incomplete-type
+         (tmpl-replace-in-type (List 'node field-type ...)
+                               ([node (U node/incomplete-type
+                                         mapping/placeholder-type ...)] ...)))]
+
+@chunk[<define-ids>
+       (define-temp-ids "~a/make-with-promises" (node ...))
+       (define-temp-ids "~a/with-promises-type" (node ...))]
 
 @subsection{Processing the placeholders}
 
diff --git a/graph/graph/queue.lp2.rkt b/graph/graph/queue.lp2.rkt
index ef29717..637447b 100644
--- a/graph/graph/queue.lp2.rkt
+++ b/graph/graph/queue.lp2.rkt
@@ -201,9 +201,9 @@ as values.
              (list (set-add past-queue element)
                    (combine-results element result result-acc)
                    #;(if (hash-has-key? result-hash element)
-                         (error (string-append
-                                 "Duplicate key in fold-queue-sets."
-                                 "Are you using mutable elements?"))
+                         (error (~a "Duplicate key " element
+                                    " in fold-queue-sets."
+                                    "Are you using mutable elements?"))
                          (hash-set result-hash element result))
                    new-acc))))]
 
@@ -372,7 +372,8 @@ was a tag requested.
                                 racket/syntax
                                 "../lib/low-untyped.rkt")
                     "../lib/low.rkt"
-                    racket/set)
+                    racket/set
+                    racket/format)
            
            (provide fold-queue
                     map-queue
diff --git a/graph/graph/rewrite-type.lp2.rkt b/graph/graph/rewrite-type.lp2.rkt
index 14a73c1..92a4c53 100644
--- a/graph/graph/rewrite-type.lp2.rkt
+++ b/graph/graph/rewrite-type.lp2.rkt
@@ -1,6 +1,7 @@
 #lang debug scribble/lp2
 @(require "../lib/doc.rkt")
 @doc-lib-setup
+@(require racket/format)
 
 @title[#:style manual-doc-style]{Rewriting data structures and their types}
 
@@ -246,8 +247,8 @@ Handling freer forms of unions causes some problems:
 
 These issues and possible solutions are addressed in more
 detail in the 
-@hyperlink[(string-append "https://phc.fogbugz.com/f/cases/54/"
-                          "Rethink-how-to-do-the-multi-step-types-more-inside")]
+@hyperlink[(~a "https://phc.fogbugz.com/f/cases/54/"
+               "Rethink-how-to-do-the-multi-step-types-more-inside")]
 {FogBugz case 54}.
 
 @section[#:tag "sec:fold"]{Folding over an instance}
diff --git a/graph/type-expander/type-expander.lp2.rkt b/graph/type-expander/type-expander.lp2.rkt
index 9510d8e..79f6196 100644
--- a/graph/type-expander/type-expander.lp2.rkt
+++ b/graph/type-expander/type-expander.lp2.rkt
@@ -39,10 +39,9 @@ contain the expander procedure, or directly an expander procedure.
                [else
                 (raise-argument-error
                  'prop:type-expander-guard
-                 (string-append
-                  "an exact non-negative integer designating a field index "
-                  "within the structure that should contain a procedure of "
-                  "arity 1, or a procedure of arity 1.")
+                 (~a "an exact non-negative integer designating a field index "
+                     "within the structure that should contain a procedure of "
+                     "arity 1, or a procedure of arity 1.")
                  val)]))]
 
 If the value is a field index, it should be within bounds. The
@@ -832,9 +831,10 @@ in @tc[racket], not @tc[typed/racket]).
 
 @chunk[<module-expander>
        (module expander racket
-         (require racket)
-         (require syntax/parse)
-         (require syntax/stx)
+         (require racket
+                  syntax/parse
+                  syntax/stx
+                  racket/format)
          
          (require (for-template typed/racket))