From f71aad515d95107da81a3f70d080e75675ce87e2 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 11 Jul 2018 22:11:28 -0700
Subject: compile-file: support hash bang.

* share/txr/stdlib/compiler.tl (usr:compile-file): Check for a
hash bang line in the source file. If so, propagate it
to the compiled file.

* txr.1: Documented existing support for hash bang in .tlo
files, and the translation of hash bang from .tl to .tlo.
---
 share/txr/stdlib/compiler.tl |  4 ++++
 txr.1                        | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/share/txr/stdlib/compiler.tl b/share/txr/stdlib/compiler.tl
index 56db42b2..5b194263 100644
--- a/share/txr/stdlib/compiler.tl
+++ b/share/txr/stdlib/compiler.tl
@@ -1595,6 +1595,10 @@
       (with-resources ((in-stream (car streams) (close-stream in-stream))
                        (out-stream (cadr streams) (close-stream out-stream))
                        (out (new list-builder)))
+        (iflet ((line (get-line in-stream))
+                ((starts-with "#!" line)))
+          (put-line line out-stream)
+          (seek-stream in-stream 0 :from-start))
         (labels ((compile-form (form)
                    (unless (atom form)
                      (caseq (car form)
diff --git a/txr.1 b/txr.1
index 9941c972..0a377670 100644
--- a/txr.1
+++ b/txr.1
@@ -62306,6 +62306,17 @@ special variable has no influence on this.
 Circular structures in compiled literals are preserved; on loading, similar
 circular structures are reproduced.
 
+.SS* Treatment of The Hash Bang Line
+
+When a source file begins with the
+.code #!
+("hash-bang") character sequence, the file compiler propagates that
+line to the compiled file, verbatim.
+
+\*(TX supports the hash bang mechanism in compiled
+.code .tlo
+files, thereby allowing compiled scripts to be executable.
+
 .coNP Function @ compile-toplevel
 .synb
 .mets (compile-toplevel < form << expanded-p )
-- 
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