diff --git a/doc/ngrams/ng1 b/doc/ngrams/ng1
new file mode 100755
index 000000000..bc1271b26
--- /dev/null
+++ b/doc/ngrams/ng1
@@ -0,0 +1 @@
+mlr --nidx --from gsl-2000.txt put -q -f ngfuncs.mlr -f ng1.mlr
diff --git a/doc/ngrams/ng1.mlr b/doc/ngrams/ng1.mlr
new file mode 100755
index 000000000..d2f0c1249
--- /dev/null
+++ b/doc/ngrams/ng1.mlr
@@ -0,0 +1,45 @@
+# ================================================================
+begin {
+  if (isabsent(@olen)) {
+    @olen = 16;
+  }
+  if (isabsent(@ocount)) {
+    @ocount = 16;
+  }
+}
+
+# ================================================================
+for (_, v in $*) {
+  if (string(v) == "inf" || string(v) == "nan") {
+    continue;
+  }
+  int n = strlen(v);
+  for (int i = 0; i < n; i += 1) {
+    str a = substr(v, i, i);
+    @a_histo[a] += 1;
+  }
+}
+
+# ================================================================
+end {
+  #dump;
+  # Define this in this scope else it'll be scoped to the for-loop.
+  map a_cmf = {};
+
+  a_cmf = compute_cmf_from_histo(@a_histo);
+
+  #print "A CMF";
+  #dump a_cmf;
+
+  for (int oi = 0; oi < @ocount; oi += 1) {
+    str out = "";
+    for (int i = 0; i < @olen; i += 1) {
+      str oa = sample_from_cmf(a_cmf);
+      if (oa == "") {
+        break;
+      }
+      out .= oa;
+    }
+    print out;
+  }
+}
diff --git a/doc/ngrams/ng2 b/doc/ngrams/ng2
new file mode 100755
index 000000000..276226af4
--- /dev/null
+++ b/doc/ngrams/ng2
@@ -0,0 +1 @@
+mlr --nidx --from gsl-2000.txt put -q -f ngfuncs.mlr -f ng2.mlr
diff --git a/doc/ngrams/ng2.mlr b/doc/ngrams/ng2.mlr
index f889ada85..1bf87ca1a 100755
--- a/doc/ngrams/ng2.mlr
+++ b/doc/ngrams/ng2.mlr
@@ -14,11 +14,11 @@ for (_, v in $*) {
     continue;
   }
   int n = strlen(v);
-  if (n >= 2) {
+  if (n >= 1) {
     str a = substr(v, 0, 0);
     @a_histo[a] += 1;
 
-    for (int i = 0; i < n-3; i += 1) {
+    for (int i = 0; i < n-1; i += 1) {
       str a = substr(v, i, i);
       str b = substr(v, i+1, i+1);
       @ab_histo[a][b] += 1;
@@ -28,11 +28,10 @@ for (_, v in $*) {
 
 # ================================================================
 end {
-
   #dump;
-
-  map a_cmf     = {};
-  map ab_cmf    = {};
+  # Define these in this scope else they'll be scoped to the for-loops.
+  map a_cmf  = {};
+  map ab_cmf = {};
 
   a_cmf = compute_cmf_from_histo(@a_histo);
 
diff --git a/doc/ngrams/ng3 b/doc/ngrams/ng3
new file mode 100755
index 000000000..a40947f1d
--- /dev/null
+++ b/doc/ngrams/ng3
@@ -0,0 +1 @@
+mlr --nidx --from gsl-2000.txt put -q -f ngfuncs.mlr -f ng3.mlr
diff --git a/doc/ngrams/ng3.mlr b/doc/ngrams/ng3.mlr
index 6fdcd24a2..8c9687fba 100755
--- a/doc/ngrams/ng3.mlr
+++ b/doc/ngrams/ng3.mlr
@@ -20,7 +20,7 @@ for (_, v in $*) {
     @a_histo[a] += 1;
     @ab_histo[a][b] += 1;
 
-    for (int i = 0; i < n-3; i += 1) {
+    for (int i = 0; i < n-2; i += 1) {
       str a = substr(v, i, i);
       str b = substr(v, i+1, i+1);
       str c = substr(v, i+2, i+2);
@@ -31,12 +31,11 @@ for (_, v in $*) {
 
 # ================================================================
 end {
-
   #dump;
-
-  map a_cmf     = {};
-  map ab_cmf    = {};
-  map abc_cmf   = {}; # xxx weirdness when these aren't predeclared as map ...
+  # Define these in this scope else they'll be scoped to the for-loops.
+  map a_cmf   = {};
+  map ab_cmf  = {};
+  map abc_cmf = {};
 
   a_cmf = compute_cmf_from_histo(@a_histo);
 
diff --git a/doc/ngrams/ng4 b/doc/ngrams/ng4
new file mode 100755
index 000000000..10bf93f13
--- /dev/null
+++ b/doc/ngrams/ng4
@@ -0,0 +1 @@
+mlr --nidx --from gsl-2000.txt put -q -f ngfuncs.mlr -f ng4.mlr
diff --git a/doc/ngrams/ng4.mlr b/doc/ngrams/ng4.mlr
index 8fe4bac24..f7d6c113d 100755
--- a/doc/ngrams/ng4.mlr
+++ b/doc/ngrams/ng4.mlr
@@ -34,13 +34,12 @@ for (_, v in $*) {
 
 # ================================================================
 end {
-
   #dump;
-
-  map a_cmf     = {};
-  map ab_cmf    = {};
-  map abc_cmf   = {}; # xxx weirdness when these aren't predeclared as map ...
-  map abcd_cmf  = {};
+  # Define these in this scope else they'll be scoped to the for-loops.
+  map a_cmf    = {};
+  map ab_cmf   = {};
+  map abc_cmf  = {};
+  map abcd_cmf = {};
 
   a_cmf = compute_cmf_from_histo(@a_histo);
 
diff --git a/doc/ngrams/ng5 b/doc/ngrams/ng5
new file mode 100755
index 000000000..fb27a084b
--- /dev/null
+++ b/doc/ngrams/ng5
@@ -0,0 +1 @@
+mlr --nidx --from gsl-2000.txt put -q -f ngfuncs.mlr -f ng5.mlr
diff --git a/doc/ngrams/ng5.mlr b/doc/ngrams/ng5.mlr
index d4053ec34..8a1c670cc 100755
--- a/doc/ngrams/ng5.mlr
+++ b/doc/ngrams/ng5.mlr
@@ -37,9 +37,7 @@ for (_, v in $*) {
 
 # ================================================================
 end {
-
   #dump;
-
   # Define these in this scope else they'll be scoped to the for-loops.
   map a_cmf     = {};
   map ab_cmf    = {};
diff --git a/doc/ngrams/ngfuncs.mlr b/doc/ngrams/ngfuncs.mlr
index 0d6c729d2..7f93665b6 100644
--- a/doc/ngrams/ngfuncs.mlr
+++ b/doc/ngrams/ngfuncs.mlr
@@ -1,6 +1,6 @@
 
 # ================================================================
-func compute_sum_from_histo(map histo) {
+func compute_sum_from_histo(map histo) : num {
   num sum = 0;
   for (k, n in histo) {
     sum += n;
@@ -9,7 +9,7 @@ func compute_sum_from_histo(map histo) {
 }
 
 # ----------------------------------------------------------------
-func compute_pmf_from_histo(map histo) {
+func compute_pmf_from_histo(map histo)  : map {
   num sum = compute_sum_from_histo(histo);
   num cumu = 0.0;
   map pmf = {};
@@ -21,7 +21,7 @@ func compute_pmf_from_histo(map histo) {
 }
 
 # ----------------------------------------------------------------
-func compute_cmf_from_pmf(map pmf) {
+func compute_cmf_from_pmf(map pmf)  : map {
   num cumu = 0.0;
   map cmf = {};
   for (k, p in pmf) {
@@ -32,12 +32,12 @@ func compute_cmf_from_pmf(map pmf) {
 }
 
 # ----------------------------------------------------------------
-func compute_cmf_from_histo(map histo) {
+func compute_cmf_from_histo(map histo)  : map {
   return compute_cmf_from_pmf(compute_pmf_from_histo(histo));
 }
 
 # ----------------------------------------------------------------
-func sample_from_cmf(var cmf) {
+func sample_from_cmf(var cmf) : str {
   u = urand();
   output = "";
   for (k, c in cmf) {
diff --git a/doc/ngrams/ngx.mlr b/doc/ngrams/ngx.mlr
deleted file mode 100644
index 2a15f6ec7..000000000
--- a/doc/ngrams/ngx.mlr
+++ /dev/null
@@ -1,121 +0,0 @@
-# ================================================================
-begin {
-  if (isabsent(@olen)) {
-    @olen = 16;
-  }
-  if (isabsent(@ocount)) {
-    @ocount = 16;
-  }
-}
-
-# ================================================================
-for (_, v in $*) {
-  if (string(v) == "inf" || string(v) == "nan") {
-    continue;
-  }
-  int n = strlen(v);
-  if (n >= 4) {
-    str a = substr(v, 0, 0);
-    str b = substr(v, 1, 1);
-    str c = substr(v, 2, 2);
-    str d = substr(v, 3, 3);
-    @a_histo[a] += 1;
-    @ab_histo[a][b] += 1;
-    @abc_histo[a][b][c] += 1;
-    @abcd_histo[a][b][c][d] += 1;
-
-    for (int i = 0; i < n-4; i += 1) {
-      str a = substr(v, i, i);
-      str b = substr(v, i+1, i+1);
-      str c = substr(v, i+2, i+2);
-      str d = substr(v, i+3, i+3);
-      str e = substr(v, i+4, i+4);
-      @abcde_histo[a][b][c][d][e] += 1;
-    }
-  }
-}
-
-# ================================================================
-end {
-
-  #dump;
-
-  #map a_cmf     = {};
-  #map ab_cmf    = {};
-  #map abc_cmf   = {}; # xxx weirdness when these aren't predeclared as map ...
-  #map abcd_cmf  = {};
-  #map abcde_cmf = {};
-
-  a_cmf = compute_cmf_from_histo(@a_histo);
-
-  print "A CMF";
-  dump a_cmf;
-
-  for (a in @ab_histo) {
-    #ab_cmf[a] = compute_cmf_from_histo(@ab_histo[a]);
-    foo = compute_cmf_from_histo(@ab_histo[a]);
-    print "foo:";
-    dump foo;
-    ab_cmf[a] = foo;
-    print "ab_cmf:";
-    dump ab_cmf;
-  }
-
-  print "AB CMF";
-  dump ab_cmf;
-
-#  for (a in @abc_histo) {
-#    for (b in @abc_histo[a]) {
-#      abc_cmf[a][b] = compute_cmf_from_histo(@abc_histo[a][b]);
-#    }
-#  }
-#
-#  print "ABC CMF";
-#  dump abc_cmf;
-#
-#  for (a in @abcd_histo) {
-#    for (b in @abcd_histo[a]) {
-#      for (c in @abcd_histo[a][b]) {
-#        abcd_cmf[a][b][c] = compute_cmf_from_histo(@abcd_histo[a][b][c]);
-#      }
-#    }
-#  }
-#
-#  print "ABCD CMF";
-#  dump abcd_cmf;
-#
-#  for (a in @abcde_histo) {
-#    for (b in @abcde_histo[a]) {
-#      for (c in @abcde_histo[a][b]) {
-#        for (d in @abcde_histo[a][b][c]) {
-#          abcde_cmf[a][b][c][d] = compute_cmf_from_histo(@abcde_histo[a][b][c][d]);
-#        }
-#      }
-#    }
-#  }
-#
-#  print "ABCDE CMF";
-#  dump abcde_cmf;
-#
-#  for (int oi = 0; oi < @ocount; oi += 1) {
-#    str oa = sample_from_cmf(a_cmf);
-#    str ob = sample_from_cmf(ab_cmf[oa]);
-#    str oc = sample_from_cmf(abc_cmf[oa][ob]);
-#    str od = sample_from_cmf(abcd_cmf[oa][ob][oc]);
-#    str out = oa . ob . oc . od;
-#
-#    for (int i = 4; i < @olen; i += 1) {
-#      str oe = sample_from_cmf(abcde_cmf[oa][ob][oc][od]);
-#      if (oe == "") {
-#        break;
-#      }
-#      out .= oe;
-#      oa = ob;
-#      ob = oc;
-#      oc = od;
-#      od = oe;
-#    }
-#    print out;
-#  }
-
-}