From f690959ef59004ba00d2d54073c9b8265e5b6d57 Mon Sep 17 00:00:00 2001
From: Leah Neukirchen <leah@vuxu.org>
Date: Thu, 1 Dec 2022 21:03:45 +0100
Subject: add lines

---
 mew.scm        | 18 +++++++++++++++++-
 mew.svnwiki    |  9 +++++++++
 tests/test.mew |  6 +++++-
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/mew.scm b/mew.scm
index 7f491b9..4caebd1 100644
--- a/mew.scm
+++ b/mew.scm
@@ -11,7 +11,7 @@
      imp inc inject into
      juxt
      keys
-     len loc
+     len lines loc
      mod
      negate
      odometer one-of op op*
@@ -823,6 +823,22 @@
                                  (read-string #f (current-input-port)))))
           (else              (error "no slurp defined"))))
 
+  (define lines
+    (case-lambda
+      (() read-line)
+      ((x) (cond ((input-port? x)
+                  (lambda ()
+                    (read-line x)))
+                 ((string? x)
+                  (let ((file (open-input-file x)))
+                    (lambda ()
+                      (let ((line (read-line file)))
+                        (when (eof-object? line)
+                          (close-input-port file))
+                        line))))
+                 (else
+                  (error "can't read lines"))))))
+
   (define (hash-table->generator h)
     (make-for-each-generator (lambda (f t)
                                (hash-table-for-each t (lambda (k v)
diff --git a/mew.svnwiki b/mew.svnwiki
index 6de85b1..c705e29 100644
--- a/mew.svnwiki
+++ b/mew.svnwiki
@@ -304,6 +304,15 @@ If {{<obj>}} is an input-port, read all data into a string.
 If {{<obj>}} is a string, read all data from the file named {{<<obj>>}.
 If {{<obj>}} is false, read all data from {{*current-input-port*}}.
 
+<procedure>(lines [<obj>])</procedure>
+
+If {{<obj>}} is missing, return {{read-line}} (a generator that
+reads lines from {{*current-input-port*}}).
+If {{<obj>}} is an input-port, return a generator that reads lines
+from {{<obj>}}.
+If {{<obj>}} is a string, return a generator that reads lines
+from the file named {{<<obj>>} and closes it on EOF.
+
 
 == Equality
 
diff --git a/tests/test.mew b/tests/test.mew
index 4bcce7f..92eb35c 100644
--- a/tests/test.mew
+++ b/tests/test.mew
@@ -427,7 +427,11 @@
 
 (test-group "slurp"
   (test #t (string? (slurp "/usr/bin/chicken-status")))
-  (test-error (string? (slurp "/dev/null/noexist"))))
+  (test-error (slurp "/dev/null/noexist")))
+
+(test-group "lines"
+  (test #t (string? ((lines "/usr/bin/chicken-status"))))
+  (test-error (lines "/dev/null/noexist")))
 
 (test-group "gen"
   (test '(1 2 3) (into '() (gen '(1 2 3))))
-- 
cgit 1.4.1