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diff --git a/src/interp/cstream.boot b/src/interp/cstream.boot
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+-- Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
+-- All rights reserved.
+--
+-- Redistribution and use in source and binary forms, with or without
+-- modification, are permitted provided that the following conditions are
+-- met:
+--
+--     - Redistributions of source code must retain the above copyright
+--       notice, this list of conditions and the following disclaimer.
+--
+--     - Redistributions in binary form must reproduce the above copyright
+--       notice, this list of conditions and the following disclaimer in
+--       the documentation and/or other materials provided with the
+--       distribution.
+--
+--     - Neither the name of The Numerical ALgorithms Group Ltd. nor the
+--       names of its contributors may be used to endorse or promote products
+--       derived from this software without specific prior written permission.
+--
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+-- IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+-- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+-- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+-- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+-- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+-- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+-- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+import '"sys-macros"
+
+)package "BOOT"
+
+--% Stream Utilities
+ 
+npNull x== StreamNull x
+ 
+StreamNull x==
+  null x or EQCAR (x,"nullstream") => true
+  while EQCAR(x,"nonnullstream") repeat
+          st:=APPLY(CADR x,CDDR x)
+          RPLACA(x,CAR st)
+          RPLACD(x,CDR st)
+  EQCAR(x,"nullstream")
+ 
+Delay(f,x)==cons("nonnullstream",[f,:x])
+ 
+StreamNil:= ["nullstream"]
+ 
+incRgen s==Delay(function incRgen1,[s])
+ 
+incRgen1(:z)==
+        [s]:=z
+        a:=shoeread_-line s
+        if NULL a
+        then (CLOSE s;StreamNil)
+
+        else cons(a,incRgen s)
+ 
+incIgen n==Delay(function incIgen1,[n])
+incIgen1(:z)==
+        [n]:=z
+        n:=n+1
+        cons(n,incIgen n)
+ 
+incZip(g,f1,f2)==Delay(function incZip1,[g,f1,f2])
+incZip1(:z)==
+     [g,f1,f2]:=z
+     StreamNull f1 => StreamNil
+     StreamNull f2 => StreamNil
+     cons(FUNCALL(g,car f1,car f2),incZip(g,cdr f1,cdr f2))
+ 
+incAppend(x,y)==Delay(function incAppend1,[x,y])
+ 
+incAppend1(:z)==
+     [x,y]:=z
+     if StreamNull x
+     then if StreamNull y
+          then StreamNil
+          else y
+     else cons(car x,incAppend(cdr x,y))
+ 
+next(f,s)==Delay(function next1,[f,s])
+next1(:z)==
+      [f,s]:=z
+      StreamNull s=> StreamNil
+      h:= APPLY(f, [s])
+      incAppend(car h,next(f,cdr h))
+ 
+nextown(f,g,s)==Delay(function nextown1,[f,g,s])
+nextown1 (:z)==
+      [f,g,s]:=z
+      StreamNull s=>
+           spadcall1 g
+           StreamNil
+      StreamNull s
+      h:=spadcall2 (f, s)
+      incAppend(car h,nextown(f,g,cdr h))
+ 
+nextown2(f,g,e,x)==nextown(cons(f,e),cons(g,e),x)
+ 
+spadcall1(g)==
+    [impl, :env] := g
+    APPLY(impl, [env])
+ 
+spadcall2(f,args) ==
+    [impl, :env] := f
+    APPLY(impl, [args, env])