From db56b1cc0ab8d62d0ba7c49ee1bc3fd6f3c0ea1d Mon Sep 17 00:00:00 2001
From: Timothy Sample <samplet@ngyro.com>
Date: Tue, 16 Oct 2018 15:26:40 -0400
Subject: [PATCH] Add for-loop semantics

* geesh/shell.scm (sh:for): New public function.
* .dir-locals.el: Indent it nicely.
---
 .dir-locals.el  |  1 +
 geesh/shell.scm | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/.dir-locals.el b/.dir-locals.el
index 10deffe..c5c6695 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -9,6 +9,7 @@
    (eval . (put '<sh-with-redirects> 'scheme-indent-function 1))
    (eval . (put 'call-with-backquoted-input-port 'scheme-indent-function 1))
    (eval . (put 'make-script 'scheme-indent-function 1))
+   (eval . (put 'sh:for 'scheme-indent-function 2))
    (eval . (put 'sh:subshell 'scheme-indent-function 1))
    (eval . (put 'sh:substitute-command 'scheme-indent-function 1))
    (eval . (put 'sh:with-redirects 'scheme-indent-function 2)))))
diff --git a/geesh/shell.scm b/geesh/shell.scm
index 10e6f84..b42eb78 100644
--- a/geesh/shell.scm
+++ b/geesh/shell.scm
@@ -8,6 +8,7 @@
   #:export (sh:and
             sh:exec-let
             sh:exec
+            sh:for
             sh:not
             sh:or
             sh:pipeline
@@ -294,3 +295,16 @@ run @var{thunk2}."
   (if (string=? (var-ref* env "?") "0")
       (set-var! env "?" "1")
       (set-var! env "?" "0")))
+
+
+;;; Loops.
+
+(define (sh:for env bindings thunk)
+  "Run @var{thunk} for each binding in @var{bindings}.  The value of
+@var{bindings} have the form @code{(@var{name} (@var{value} ...))}."
+  (set-var! env "?" "0")
+  (match-let (((name (values ...)) bindings))
+    (for-each (lambda (value)
+                (set-var! env name value)
+                (thunk))
+              values)))