From a5bb9da6ea3f69a0e03329b94dcb3bf1c3315ed5 Mon Sep 17 00:00:00 2001
From: Daniel Llorens <daniel.llorens@bluewin.ch>
Date: Tue, 8 Sep 2015 16:57:30 +0200
Subject: [PATCH] New functions (array-for-each-cell,
 array-for-each-cell-in-order)

* libguile/array-map.c (scm_i_array_rebase, scm_array_for_each_cell):
  New functions. Export scm_array_for_each_cell() as
  (array-for-each-cell).

  (array-for-each-cell-in-order): Define additional export.

* libguile/array-map.h (scm_i_array_rebase, scm_array_for_each_cell):
  Add prototypes.

* doc/ref/api-compound.texi: New section 'Arrays as arrays of
  arrays'. Move the documentation for (array-from), (array-from*) and
  (array-amend!) in here. Add documentation for (array-for-each-cell).

* test-suite/tests/array-map.test: Renamed from
  test-suite/tests/ramap.test, fix module name. Add tests for
  (array-for-each-cell).

* test-suite/Makefile.am: Apply rename array-map.test -> ramap.test.

* doc/ref/api-compound.texi: Minor documentation fixes.
---
 doc/ref/api-compound.texi                     | 263 +++++++++++-------
 libguile/array-map.c                          | 260 ++++++++++++++++-
 libguile/array-map.h                          |   4 +
 libguile/arrays.c                             |   5 +-
 test-suite/Makefile.am                        |   2 +-
 .../tests/{ramap.test => array-map.test}      |  35 ++-
 6 files changed, 463 insertions(+), 106 deletions(-)
 rename test-suite/tests/{ramap.test => array-map.test} (94%)

diff --git a/doc/ref/api-compound.texi b/doc/ref/api-compound.texi
index 6d1e118b6..936b4956c 100644
--- a/doc/ref/api-compound.texi
+++ b/doc/ref/api-compound.texi
@@ -1203,6 +1203,7 @@ dimensional arrays.
 * Array Syntax::                
 * Array Procedures::            
 * Shared Arrays::               
+* Arrays as arrays of arrays::
 * Accessing Arrays from C::     
 @end menu
 
@@ -1682,104 +1683,6 @@ sample points are enough because @var{mapfunc} is linear.
 Return the element at @code{(idx @dots{})} in @var{array}.
 @end deffn
 
-@deffn {Scheme Procedure} array-from array idx @dots{}
-@deffnx {C Function} scm_array_from (array, idxlist)
-If the length of @var{idxlist} equals the rank @math{n} of
-@var{array}, return the element at @code{(idx @dots{})}, just like
-@code{(array-ref array idx @dots{})}. If, however, the length @math{k}
-of @var{idxlist} is shorter than @math{n}, then return the shared
-@math{(n-k)}-rank prefix cell of @var{array} given by @var{idxlist}.
-
-For example:
-
-@example
-@lisp
-(array-from #2((a b) (c d)) 0) @result{} #(a b)
-(array-from #2((a b) (c d)) 1) @result{} #(c d)
-(array-from #2((a b) (c d)) 1 1) @result{} d
-(array-from #2((a b) (c d))) @result{} #2((a b) (c d))
-@end lisp
-@end example
-
-@code{(apply array-from array indices)} is equivalent to
-
-@lisp
-(let ((len (length indices)))
-  (if (= (array-rank a) len)
-    (apply array-ref a indices)
-    (apply make-shared-array a
-           (lambda t (append indices t))
-           (drop (array-dimensions a) len))))
-@end lisp
-
-The name `from' comes from the J language.
-@end deffn
-
-@deffn {Scheme Procedure} array-from* array idx @dots{}
-@deffnx {C Function} scm_array_from_s (array, idxlist)
-Like @code{(array-from array idx @dots{})}, but return a 0-rank shared
-array if the length of @var{idxlist} matches the rank of
-@var{array}. This can be useful when using @var{ARRAY} as destination
-of copies.
-
-Compare:
-
-@example
-@lisp
-(array-from #2((a b) (c d)) 1 1) @result{} d
-(array-from* #2((a b) (c d)) 1) @result{} #0(d)
-(define a (make-array 'a 2 2))
-(array-fill! (array-from* a 1 1) 'b)
-a @result{} #2((a a) (a b)).
-(array-fill! (array-from a 1 1) 'b) @result{} error: not an array
-@end lisp
-@end example
-
-@code{(apply array-from* array indices)} is equivalent to
-
-@lisp
-(apply make-shared-array a
-  (lambda t (append indices t))
-  (drop (array-dimensions a) (length indices)))
-@end lisp
-@end deffn
-
-
-@deffn {Scheme Procedure} array-amend! array x idx @dots{}
-@deffnx {C Function} scm_array_amend_x (array, x, idxlist)
-If the length of @var{idxlist} equals the rank @math{n} of
-@var{array}, set the element at @code{(idx @dots{})} of @var{array} to
-@var{x}, just like @code{(array-set! array x idx @dots{})}. If,
-however, the length @math{k} of @var{idxlist} is shorter than
-@math{n}, then copy the @math{(n-k)}-rank array @var{x}
-into @math{(n-k)}-rank prefix cell of @var{array} given by
-@var{idxlist}. In this case, the last @math{(n-k)} dimensions of
-@var{array} and the dimensions of @var{x} must match exactly.
-
-This function returns the modified @var{array}.
-
-For example:
-
-@example
-@lisp
-(array-amend! (make-array 'a 2 2) b 1 1) @result{} #2((a a) (a b))
-(array-amend! (make-array 'a 2 2) #(x y) 1) @result{} #2((a a) (x y))
-@end lisp
-@end example
-
-@code{(apply array-amend! array x indices)} is equivalent to
-
-@lisp
-(let ((len (length indices)))
-  (if (= (array-rank array) len)
-    (apply array-set! array x indices)
-    (array-copy! x (apply array-from array indices)))
-  array)
-@end lisp
-
-The name `amend' comes from the J language.
-@end deffn
-
 
 @deffn {Scheme Procedure} shared-array-increments array
 @deffnx {C Function} scm_shared_array_increments (array)
@@ -1833,6 +1736,170 @@ have smaller rank than @var{array}.
 @end lisp
 @end deffn
 
+@node Arrays as arrays of arrays
+@subsubsection Arrays as arrays of arrays
+
+The functions in this section allow you to treat an array of rank
+@math{n} as an array of lower rank @math{n-k} where the elements are
+themselves arrays (`cells') of rank @math{k}. This replicates some of
+the functionality of `enclosed arrays', a feature of old Guile that was
+removed before @w{version 2.0}. However, these functions do not require
+a special type and operate on any array.
+
+When we operate on an array in this way, we speak of the first @math{k}
+dimensions of the array as the @math{k}-`frame' of the array, while the
+last @math{n-k} dimensions are the dimensions of the
+@math{n-k}-`cell'. For example, a 2D-array (a matrix) can be seen as a
+1D array of rows. In this case, the rows are the 1-cells of the array.
+
+@deffn {Scheme Procedure} array-from array idx @dots{}
+@deffnx {C Function} scm_array_from (array, idxlist)
+If the length of @var{idxlist} equals the rank @math{n} of
+@var{array}, return the element at @code{(idx @dots{})}, just like
+@code{(array-ref array idx @dots{})}. If, however, the length @math{k}
+of @var{idxlist} is shorter than @math{n}, then return the shared
+@math{(n-k)}-rank cell of @var{array} given by @var{idxlist}.
+
+For example:
+
+@lisp
+(array-from #2((a b) (c d)) 0) @result{} #(a b)
+(array-from #2((a b) (c d)) 1) @result{} #(c d)
+(array-from #2((a b) (c d)) 1 1) @result{} d
+(array-from #2((a b) (c d))) @result{} #2((a b) (c d))
+@end lisp
+
+@code{(apply array-from array indices)} is equivalent to
+
+@lisp
+(let ((len (length indices)))
+  (if (= (array-rank a) len)
+    (apply array-ref a indices)
+    (apply make-shared-array a
+           (lambda t (append indices t))
+           (drop (array-dimensions a) len))))
+@end lisp
+
+The name `from' comes from the J language.
+@end deffn
+
+@deffn {Scheme Procedure} array-from* array idx @dots{}
+@deffnx {C Function} scm_array_from_s (array, idxlist)
+Like @code{(array-from array idx @dots{})}, but return a 0-rank shared
+array if the length of @var{idxlist} matches the rank of
+@var{array}. This can be useful when using @var{ARRAY} as a place to
+write into.
+
+Compare:
+
+@lisp
+(array-from #2((a b) (c d)) 1 1) @result{} d
+(array-from* #2((a b) (c d)) 1) @result{} #0(d)
+(define a (make-array 'a 2 2))
+(array-fill! (array-from* a 1 1) 'b)
+a @result{} #2((a a) (a b)).
+(array-fill! (array-from a 1 1) 'b) @result{} error: not an array
+@end lisp
+
+@code{(apply array-from* array indices)} is equivalent to
+
+@lisp
+(apply make-shared-array a
+  (lambda t (append indices t))
+  (drop (array-dimensions a) (length indices)))
+@end lisp
+@end deffn
+
+
+@deffn {Scheme Procedure} array-amend! array x idx @dots{}
+@deffnx {C Function} scm_array_amend_x (array, x, idxlist)
+If the length of @var{idxlist} equals the rank @math{n} of
+@var{array}, set the element at @code{(idx @dots{})} of @var{array} to
+@var{x}, just like @code{(array-set! array x idx @dots{})}. If,
+however, the length @math{k} of @var{idxlist} is shorter than
+@math{n}, then copy the @math{(n-k)}-rank array @var{x}
+into the @math{(n-k)}-cell of @var{array} given by
+@var{idxlist}. In this case, the last @math{(n-k)} dimensions of
+@var{array} and the dimensions of @var{x} must match exactly.
+
+This function returns the modified @var{array}.
+
+For example:
+
+@lisp
+(array-amend! (make-array 'a 2 2) b 1 1) @result{} #2((a a) (a b))
+(array-amend! (make-array 'a 2 2) #(x y) 1) @result{} #2((a a) (x y))
+@end lisp
+
+Note that @code{array-amend!} will expect elements, not arrays, when the
+destination has rank 0. One can work around this using
+@code{array-from*} instead.
+
+@lisp
+(array-amend! (make-array 'a 2 2) #0(b) 1 1) @result{} #2((a a) (a #0(b)))
+(let ((a (make-array 'a 2 2))) (array-copy! #0(b) (array-from* a 1 1)) a) @result{} #2((a a) (a b))
+@end lisp
+
+@code{(apply array-amend! array x indices)} is equivalent to
+
+@lisp
+(let ((len (length indices)))
+  (if (= (array-rank array) len)
+    (apply array-set! array x indices)
+    (array-copy! x (apply array-from array indices)))
+  array)
+@end lisp
+
+The name `amend' comes from the J language.
+@end deffn
+
+
+@deffn {Scheme Procedure} array-for-each-cell frame-rank op x @dots{}
+@deffnx {C Function} scm_array_for_each_cell (array, frame_rank, op, xlist)
+Each @var{x} must be an array of rank ≥ @var{frame-rank}, and
+the first @var{frame-rank} dimensions of each @var{x} must all be the
+same. @var{array-for-each-cell} calls @var{op} with each set of
+(rank(@var{x}) - @var{frame-rank})-cells from @var{x}, in unspecified order.
+
+@var{array-for-each-cell} allows you to loop over cells of any rank
+without having to carry an index list or construct slices manually. The
+cells passed to @var{op} are shared arrays of @var{X} so it is possible
+to write to them.
+
+This function returns an unspecified value.
+
+For example, to sort the rows of rank-2 array @code{a}:
+
+@lisp
+(array-for-each-cell 1 (lambda (x) (sort! x <)) a)
+@end lisp
+
+As another example, let @code{a} be a rank-2 array where each row is a 2-vector @math{(x,y)}.
+Let's compute the arguments of these vectors and store them in rank-1 array @code{b}.
+@lisp
+(array-for-each-cell 1
+  (lambda (a b)
+    (array-set! b (atan (array-ref a 1) (array-ref a 0))))
+  a b)
+@end lisp
+
+@code{(apply array-for-each-cell frame-rank op x)} is functionally
+equivalent to
+
+@lisp
+(let ((frame (take (array-dimensions (car x)) frank)))
+  (unless (every (lambda (x)
+                   (equal? frame (take (array-dimensions x) frank)))
+                 (cdr x))
+    (error))
+  (array-index-map!
+    (apply make-shared-array (make-array #t) (const '()) frame)
+    (lambda i (apply op (map (lambda (x) (apply array-from* x i)) x)))))
+@end lisp
+
+@end deffn
+
+
 @node Accessing Arrays from C
 @subsubsection Accessing Arrays from C
 
diff --git a/libguile/array-map.c b/libguile/array-map.c
index 01bebb83e..f907786fd 100644
--- a/libguile/array-map.c
+++ b/libguile/array-map.c
@@ -42,7 +42,7 @@
 
 #include "libguile/validate.h"
 #include "libguile/array-map.h"
-
+#include <assert.h>
 
 /* The WHAT argument for `scm_gc_malloc ()' et al.  */
 static const char vi_gc_hint[] = "array-indices";
@@ -629,7 +629,8 @@ SCM_DEFINE (scm_i_array_equal_p, "array-equal?", 0, 2, 1,
     return SCM_BOOL_T;
 
   while (!scm_is_null (rest))
-    { if (scm_is_false (scm_array_equal_p (ra0, ra1)))
+    {
+      if (scm_is_false (scm_array_equal_p (ra0, ra1)))
         return SCM_BOOL_F;
       ra0 = ra1;
       ra1 = scm_car (rest);
@@ -640,6 +641,261 @@ SCM_DEFINE (scm_i_array_equal_p, "array-equal?", 0, 2, 1,
 #undef FUNC_NAME
 
 
+/* Copy array descriptor with different base. */
+SCM
+scm_i_array_rebase (SCM a, size_t base)
+{
+    size_t ndim = SCM_I_ARRAY_NDIM (a);
+    SCM b = scm_words (((scm_t_bits) ndim << 17) + scm_tc7_array, 3 + ndim*3);
+    SCM_I_ARRAY_SET_V (b, SCM_I_ARRAY_V (a));
+/* FIXME do check base */
+    SCM_I_ARRAY_SET_BASE (b, base);
+    memcpy (SCM_I_ARRAY_DIMS (b), SCM_I_ARRAY_DIMS (a), sizeof (scm_t_array_dim)*ndim);
+    return b;
+}
+
+static inline size_t padtoptr(size_t d) { return (d + (sizeof (void *) - 1)) & ~(sizeof (void *) - 1); }
+
+SCM_DEFINE (scm_array_for_each_cell, "array-for-each-cell", 2, 0, 1,
+            (SCM frame_rank, SCM op, SCM args),
+            "Apply @var{op} to each of the cells of rank rank(@var{arg})-@var{frame_rank}\n"
+            "of the arrays @var{args}, in unspecified order. The first\n"
+            "@var{frame_rank} dimensions of each @var{arg} must match.\n"
+            "Rank-0 cells are passed as rank-0 arrays.\n\n"
+            "The value returned is unspecified.\n\n"
+            "For example:\n"
+            "@lisp\n"
+            ";; Sort the rows of rank-2 array A.\n\n"
+            "(array-for-each-cell 1 (lambda (x) (sort! x <)) a)\n"
+            "\n"
+            ";; Compute the arguments of the (x y) vectors in the rows of rank-2\n"
+            ";; array XYS and store them in rank-1 array ANGLES. Inside OP,\n"
+            ";; XY is a rank-1 (2-1) array, and ANGLE is a rank-0 (1-1) array.\n\n"
+            "(array-for-each-cell 1 \n"
+            "  (lambda (xy angle)\n"
+            "    (array-set! angle (atan (array-ref xy 1) (array-ref xy 0))))\n"
+            "  xys angles)\n"
+            "@end lisp")
+#define FUNC_NAME s_scm_array_for_each_cell
+{
+  int const N = scm_ilength (args);
+  int const frank = scm_to_int (frame_rank);
+  int ocd;
+  ssize_t step;
+  SCM dargs_ = SCM_EOL;
+  char const * msg;
+  scm_t_array_dim * ais;
+  int n, k;
+  ssize_t z;
+
+  /* to be allocated inside the pool */
+  scm_t_array_handle * ah;
+  SCM * args_;
+  scm_t_array_dim ** as;
+  int * rank;
+
+  ssize_t * s;
+  SCM * ai;
+  SCM ** dargs;
+  ssize_t * i;
+
+  int * order;
+  size_t * base;
+
+  /* size the pool */
+  char * pool;
+  char * pool0;
+  size_t pool_size = 0;
+  pool_size += padtoptr(N*sizeof (scm_t_array_handle));
+  pool_size += padtoptr(N*sizeof (SCM));
+  pool_size += padtoptr(N*sizeof (scm_t_array_dim *));
+  pool_size += padtoptr(N*sizeof (int));
+
+  pool_size += padtoptr(frank*sizeof (ssize_t));
+  pool_size += padtoptr(N*sizeof (SCM));
+  pool_size += padtoptr(N*sizeof (SCM *));
+  pool_size += padtoptr(frank*sizeof (ssize_t));
+
+  pool_size += padtoptr(frank*sizeof (int));
+  pool_size += padtoptr(N*sizeof (size_t));
+  pool = scm_gc_malloc (pool_size, "pool");
+
+  /* place the items in the pool */
+#define AFIC_ALLOC_ADVANCE(pool, count, type, name)    \
+  name = (void *)pool;                                 \
+  pool += padtoptr(count*sizeof (type));
+
+  pool0 = pool;
+  AFIC_ALLOC_ADVANCE (pool, N, scm_t_array_handle, ah);
+  AFIC_ALLOC_ADVANCE (pool, N, SCM, args_);
+  AFIC_ALLOC_ADVANCE (pool, N, scm_t_array_dim *, as);
+  AFIC_ALLOC_ADVANCE (pool, N, int, rank);
+
+  AFIC_ALLOC_ADVANCE (pool, frank, ssize_t, s);
+  AFIC_ALLOC_ADVANCE (pool, N, SCM, ai);
+  AFIC_ALLOC_ADVANCE (pool, N, SCM *, dargs);
+  AFIC_ALLOC_ADVANCE (pool, frank, ssize_t, i);
+
+  AFIC_ALLOC_ADVANCE (pool, frank, int, order);
+  AFIC_ALLOC_ADVANCE (pool, N, size_t, base);
+  assert((pool0+pool_size==pool) && "internal error");
+#undef AFIC_ALLOC_ADVANCE
+
+  for (n=0; scm_is_pair(args); args=scm_cdr(args), ++n)
+    {
+      args_[n] = scm_car(args);
+      scm_array_get_handle(args_[n], ah+n);
+      as[n] = scm_array_handle_dims(ah+n);
+      rank[n] = scm_array_handle_rank(ah+n);
+    }
+  /* checks */
+  msg = NULL;
+  if (frank<0)
+    msg = "bad frame rank";
+  else
+    {
+      for (n=0; n!=N; ++n)
+        {
+          if (rank[n]<frank)
+            {
+              msg = "frame too large for arguments";
+              goto check_msg;
+            }
+          for (k=0; k!=frank; ++k)
+            {
+              if (as[n][k].lbnd!=0)
+                {
+                  msg = "non-zero base index is not supported";
+                  goto check_msg;
+                }
+              if (as[0][k].ubnd!=as[n][k].ubnd)
+                {
+                  msg = "mismatched frames";
+                  goto check_msg;
+                }
+              s[k] = as[n][k].ubnd + 1;
+
+              /* this check is needed if the array cannot be entirely */
+              /* unrolled, because the unrolled subloop will be run before */
+              /* checking the dimensions of the frame. */
+              if (s[k]==0)
+                goto end;
+            }
+        }
+    }
+ check_msg: ;
+  if (msg!=NULL)
+    {
+      for (n=0; n!=N; ++n)
+        scm_array_handle_release(ah+n);
+      scm_misc_error("array-for-each-cell", msg, scm_cons_star(frame_rank, args));
+    }
+  /* prepare moving cells. */
+  for (n=0; n!=N; ++n)
+    {
+      ai[n] = scm_i_make_array(rank[n]-frank);
+      SCM_I_ARRAY_SET_V (ai[n], scm_shared_array_root(args_[n]));
+      /* FIXME scm_array_handle_base (ah+n) should be in Guile */
+      SCM_I_ARRAY_SET_BASE (ai[n], ah[n].base);
+      ais = SCM_I_ARRAY_DIMS(ai[n]);
+      for (k=frank; k!=rank[n]; ++k)
+        {
+          ais[k-frank] = as[n][k];
+        }
+    }
+  /* prepare rest list for callee. */
+  {
+    SCM *p = &dargs_;
+    for (n=0; n<N; ++n)
+      {
+        *p = scm_cons (SCM_UNSPECIFIED, SCM_EOL);
+        dargs[n] = SCM_CARLOC (*p);
+        p = SCM_CDRLOC (*p);
+      }
+  }
+  /* special case for rank 0. */
+  if (frank==0)
+    {
+      for (n=0; n<N; ++n)
+        *dargs[n] = ai[n];
+      scm_apply_0(op, dargs_);
+      for (n=0; n<N; ++n)
+        scm_array_handle_release(ah+n);
+      return SCM_UNSPECIFIED;
+    }
+  /* FIXME determine best looping order. */
+  for (k=0; k!=frank; ++k)
+    {
+      i[k] = 0;
+      order[k] = frank-1-k;
+    }
+  /* find outermost compact dim. */
+  step = s[order[0]];
+  ocd = 1;
+  for (; ocd<frank; step *= s[order[ocd]], ++ocd)
+    for (n=0; n!=N; ++n)
+      if (step*as[n][order[0]].inc!=as[n][order[ocd]].inc)
+        goto ocd_reached;
+ ocd_reached: ;
+  /* rank loop. */
+  for (n=0; n!=N; ++n)
+    base[n] = SCM_I_ARRAY_BASE(ai[n]);
+  for (;;)
+    {
+      /* unrolled loop. */
+      for (z=0; z!=step; ++z)
+        {
+          /* we are forced to create fresh array descriptors for each */
+          /* call since we don't know whether the callee will keep them, */
+          /* and Guile offers no way to copy the descriptor (since */
+          /* descriptors are immutable). Yet another reason why this */
+          /* should be in Scheme. */
+          for (n=0; n<N; ++n)
+            {
+              *dargs[n] = scm_i_array_rebase(ai[n], base[n]);
+              base[n] += as[n][order[0]].inc;
+            }
+          scm_apply_0(op, dargs_);
+        }
+      for (n=0; n<N; ++n)
+        base[n] -= step*as[n][order[0]].inc;
+      for (k=ocd; ; ++k)
+        {
+          if (k==frank)
+            goto end;
+          else if (i[order[k]]<s[order[k]]-1)
+            {
+              ++i[order[k]];
+              for (n=0; n<N; ++n)
+                base[n] += as[n][order[k]].inc;
+              break;
+            }
+          else
+            {
+              i[order[k]] = 0;
+              for (n=0; n<N; ++n)
+                base[n] += as[n][order[k]].inc*(1-s[order[k]]);
+            }
+        }
+    }
+ end:;
+  for (n=0; n<N; ++n)
+    scm_array_handle_release(ah+n);
+  return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_array_for_each_cell_in_order, "array-for-each-cell-in-order", 2, 0, 1,
+            (SCM frank, SCM op, SCM a),
+            "Same as array-for-each-cell, but visit the cells sequentially\n"
+            "and in row-major order.\n")
+#define FUNC_NAME s_scm_array_for_each_cell_in_order
+{
+  return scm_array_for_each_cell (frank, op, a);
+}
+#undef FUNC_NAME
+
+
 void
 scm_init_array_map (void)
 {
diff --git a/libguile/array-map.h b/libguile/array-map.h
index cb18a628a..acfdd5e24 100644
--- a/libguile/array-map.h
+++ b/libguile/array-map.h
@@ -37,6 +37,10 @@ SCM_API SCM scm_array_map_x (SCM ra0, SCM proc, SCM lra);
 SCM_API SCM scm_array_for_each (SCM proc, SCM ra0, SCM lra);
 SCM_API SCM scm_array_index_map_x (SCM ra, SCM proc);
 SCM_API SCM scm_array_equal_p (SCM ra0, SCM ra1);
+SCM_API SCM scm_array_for_each_cell (SCM frank, SCM op, SCM args);
+SCM_API SCM scm_array_for_each_cell_in_order (SCM frank, SCM op, SCM args);
+
+SCM_INTERNAL SCM scm_i_array_rebase (SCM a, size_t base);
 SCM_INTERNAL void scm_init_array_map (void);
 
 #endif  /* SCM_ARRAY_MAP_H */
diff --git a/libguile/arrays.c b/libguile/arrays.c
index 273c48b73..7622ea8ca 100644
--- a/libguile/arrays.c
+++ b/libguile/arrays.c
@@ -28,7 +28,6 @@
 #include <stdio.h>
 #include <errno.h>
 #include <string.h>
-#include <assert.h>
 
 #include "verify.h"
 
@@ -551,7 +550,7 @@ SCM_DEFINE (scm_array_amend_x, "array-amend!", 2, 0, 1,
         { ARRAY_FROM_GET_O }
       scm_array_handle_release(&handle);
       /* an error is still possible here if o and b don't match. */
-      /* TODO copying like this wastes the handle, and the bounds matching
+      /* FIXME copying like this wastes the handle, and the bounds matching
          behavior of array-copy! is not strict. */
       scm_array_copy_x(b, o);
     }
@@ -569,7 +568,6 @@ SCM_DEFINE (scm_array_amend_x, "array-amend!", 2, 0, 1,
 }
 #undef FUNC_NAME
 
-
 #undef ARRAY_FROM_POS
 #undef ARRAY_FROM_GET_O
 
@@ -948,6 +946,7 @@ scm_i_print_array (SCM array, SCM port, scm_print_state *pstate)
     return scm_i_print_array_dimension (&h, 0, 0, port, pstate);
 }
 
+
 void
 scm_init_arrays ()
 {
diff --git a/test-suite/Makefile.am b/test-suite/Makefile.am
index f940d78c7..98cc5f026 100644
--- a/test-suite/Makefile.am
+++ b/test-suite/Makefile.am
@@ -115,7 +115,7 @@ SCM_TESTS = tests/00-initial-env.test		\
 	    tests/r6rs-records-syntactic.test	\
 	    tests/r6rs-unicode.test		\
 	    tests/rnrs-libraries.test		\
-	    tests/ramap.test			\
+	    tests/array-map.test		\
 	    tests/random.test			\
 	    tests/rdelim.test			\
 	    tests/reader.test			\
diff --git a/test-suite/tests/ramap.test b/test-suite/tests/array-map.test
similarity index 94%
rename from test-suite/tests/ramap.test
rename to test-suite/tests/array-map.test
index bd8a434bd..3095b78f4 100644
--- a/test-suite/tests/ramap.test
+++ b/test-suite/tests/array-map.test
@@ -1,4 +1,4 @@
-;;;; ramap.test --- test array mapping functions -*- scheme -*-
+;;;; array-map.test --- test array mapping functions -*- scheme -*-
 ;;;; 
 ;;;; Copyright (C) 2004, 2005, 2006, 2009, 2013 Free Software Foundation, Inc.
 ;;;;
@@ -16,7 +16,7 @@
 ;;;; License along with this library; if not, write to the Free Software
 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
-(define-module (test-suite test-ramap)
+(define-module (test-suite test-array-map)
   #:use-module (test-suite lib))
 
 (define exception:shape-mismatch
@@ -507,3 +507,34 @@
              (b (make-typed-array 'f64 0 0 2))
              (c (make-typed-array 'f64 0 2 0)))
         (array-for-each (lambda (b c) (set! a (cons* b c a))) b c)))))
+
+;;;
+;;; array-for-each-cell
+;;;
+
+(with-test-prefix "array-for-each-cell"
+
+  (pass-if-equal "1 argument frame rank 1"
+      #2((1 3 9) (2 7 8))
+      (let* ((a (list->array 2 '((9 1 3) (7 8 2)))))
+        (array-for-each-cell 1 (lambda (a) (sort! a <)) a)
+        a))
+
+  (pass-if-equal "2 arguments frame rank 1"
+      #f64(8 -1)
+      (let* ((x (list->typed-array 'f64 2 '((9 1) (7 8))))
+             (y (f64vector 99 99)))
+        (array-for-each-cell 1 (lambda (y x) (array-set! y (- (array-ref x 0) (array-ref x 1)))) y x)
+        y))
+
+  (pass-if-equal "regression: zero-sized frame loop without unrolling"
+      99
+    (let* ((x 99)
+           (o (make-array 0. 0 3 2)))
+      (array-for-each-cell 2
+        (lambda (o a0 a1)
+          (set! x 0))
+        o
+        (make-shared-array (make-array 1. 0 1) (const '(0 0)) 0 3)
+        (make-array 2. 0 3))
+      x)))