Further small changes on the way to a reader.

docs/State-of-play.md

@@ -1,5 +1,16 @@
 # State of Play
 
+## 20260331
+
+Substrate layer `print` is written; all the building blocks for substrate
+layer `read` is in place. This will read far less than the 0.0.6, but it 
+will be extensible with read macros *written in Lisp*, so much more flexible,
+and will gradually grow to read more than the non-extensible 0.0.6 reader
+was. Pleased with myself.
+
+The new print may grow to be extensible in Lisp, as well. In fact, it will 
+have to!
+
 ## 20260326
 
 Most of the memory architecture of the new prototype is now roughed out, but

src/c/io/read.c

@@ -69,4 +69,17 @@ struct pso_pointer read_example( struct pso4 *frame,
 }
 
 
-// struct pso_pointer read
+/**
+ * Read the next object on this input stream and return a pso_pointer to it.
+ */
+struct pso_pointer read( struct pso4 *frame,
+						  struct pso_pointer frame_pointer,
+                          struct pso_pointer env ) {
+	struct pso_pointer* character = fetch_arg( frame, 0);
+	struct pso_pointer stream = fetch_arg( frame, 1);
+	struct pso_pointer readtable = fetch_arg( frame, 2);
+
+	if (nilp(stream)) {
+
+	}
+}

src/c/payloads/read_stream.c

@@ -0,0 +1,33 @@
+/**
+ *  payloads/read_stream.h
+ *
+ *  A read stream.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#include <stdio.h>
+
+#include <curl/curl.h>
+
+#include "io/fopen.h"
+#include "memory/pointer.h"
+
+
+/**
+ * Construct a cell which points to a stream open for reading.
+ * @param input the C stream to wrap.
+ * @param metadata a pointer to an associaton containing metadata on the stream.
+ * @return a pointer to the new read stream.
+ */
+struct pso_pointer make_read_stream( URL_FILE *input,
+                                      struct pso_pointer metadata ) {
+    struct pso_pointer pointer = allocate( READTV, 2);
+    struct pso2 *cell = pointer_to_object( pointer );
+
+    cell->payload.stream.stream = input;
+    cell->payload.stream.meta = metadata;
+
+    return pointer;
+}

unit-tests/string-allocation.sh

@@ -3,9 +3,9 @@
 value='"Fred"'
 expected="String cell: character 'F'"
 # set! protects "Fred" from the garbage collector.
-actual=`echo "(set! x ${value})" | target/psse -d 2>&1 | grep "$expected" | sed 's/ *\(.*\) next.*$/\1/'`
+actual=`echo "(set! x ${value})" | target/psse -d 2>&1 | grep "$expected" # | sed 's/ *\(.*\) next.*$/\1/'`
 
-if [ $? -eq 0 ]
+if [ "${expected}" = "${actual}" ]
 then
     echo "OK"
     exit 0