clean up contents and lines words; contents never outputs f now

basis/io/launcher/unix/unix-tests.factor

@@ -48,7 +48,7 @@ concurrency.promises threads unix.process ;
     try-process
 ] unit-test
 
-[ f ] [
+[ "" ] [
     "cat"
     "launcher-test-1" temp-file
     2array

basis/io/streams/string/string-tests.factor

@@ -2,6 +2,8 @@ USING: io.streams.string io kernel arrays namespaces make
 tools.test ;
 IN: io.streams.string.tests
 
+[ "" ] [ "" [ contents ] with-string-reader ] unit-test
+
 [ "line 1" CHAR: l ]
 [
     "line 1\nline 2\nline 3" <string-reader>

core/io/io-docs.factor

@@ -239,13 +239,13 @@ HELP: each-block
 { $description "Calls the quotation with successive blocks of data, until the current " { $link input-stream } " is exhausted." } ;
 
 HELP: stream-contents
-{ $values { "stream" "an input stream" } { "seq" "a string, byte array or " { $link f } } }
-{ $description "Reads the entire contents of a stream. If the stream is empty, outputs "  { $link f } "." }
+{ $values { "stream" "an input stream" } { "seq" { $or string byte-array } } }
+{ $description "Reads all elements in the given stream until the stream is exhausted. The type of the sequence depends on the stream's element type." }
 $io-error ;
 
 HELP: contents
-{ $values { "seq" "a string, byte array or " { $link f } } }
-{ $description "Reads the entire contents of a the stream stored in " { $link input-stream } ". If the stream is empty, outputs " { $link f } "." }
+{ $values { "seq" { $or string byte-array } } }
+{ $description "Reads all elements in the " { $link input-stream } " until the stream is exhausted. The type of the sequence depends on the stream's element type." }
 $io-error ;
 
 ARTICLE: "stream-protocol" "Stream protocol"

core/io/io.factor

@@ -1,7 +1,7 @@
 ! Copyright (C) 2003, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: hashtables generic kernel math namespaces make sequences
-continuations destructors assocs ;
+continuations destructors assocs combinators ;
 IN: io
 
 SYMBOLS: +byte+ +character+ ;
@@ -20,7 +20,9 @@ GENERIC: stream-flush ( stream -- )
 GENERIC: stream-nl ( stream -- )
 
 ERROR: bad-seek-type type ;
+
 SINGLETONS: seek-absolute seek-relative seek-end ;
+
 GENERIC: stream-seek ( n seek-type stream -- )
 
 : stream-print ( str stream -- ) [ stream-write ] keep stream-nl ;
@@ -68,29 +70,39 @@ SYMBOL: error-stream
 
 : bl ( -- ) " " write ;
 
-: stream-lines ( stream -- seq )
-    [ [ readln dup ] [ ] produce nip ] with-input-stream ;
-
-: lines ( -- seq )
-    input-stream get stream-lines ;
-
 <PRIVATE
 
 : each-morsel ( handler: ( data -- ) reader: ( -- data ) -- )
     [ dup ] compose swap while drop ; inline
 
+: stream-element-exemplar ( type -- exemplar )
+    {
+        { +byte+ [ B{ } ] }
+        { +character+ [ "" ] }
+    } case ;
+
+: element-exemplar ( -- exemplar )
+    input-stream get
+    stream-element-type
+    stream-element-exemplar ;
+
 PRIVATE>
 
 : each-line ( quot -- )
     [ readln ] each-morsel ; inline
 
-: stream-contents ( stream -- seq )
-    [
-        [ 65536 read-partial dup ] [ ] produce nip concat f like
-    ] with-input-stream ;
+: lines ( -- seq )
+    [ ] accumulator [ each-line ] dip { } like ;
+
+: stream-lines ( stream -- seq )
+    [ lines ] with-input-stream ;
 
 : contents ( -- seq )
-    input-stream get stream-contents ;
+    [ 65536 read-partial dup ] [ ] produce nip
+    element-exemplar concat-as ;
+
+: stream-contents ( stream -- seq )
+    [ contents ] with-input-stream ;
 
 : each-block ( quot: ( block -- ) -- )
     [ 8192 read-partial ] each-morsel ; inline

core/io/streams/byte-array/byte-array-tests.factor

@@ -1,6 +1,7 @@
 USING: tools.test io.streams.byte-array io.encodings.binary
 io.encodings.utf8 io kernel arrays strings namespaces ;
 
+[ B{ } ] [ B{ } binary [ contents ] with-byte-reader ] unit-test
 [ B{ 1 2 3 } ] [ binary [ B{ 1 2 3 } write ] with-byte-writer ] unit-test
 [ B{ 1 2 3 } ] [ { 1 2 3 } binary [ 3 read ] with-byte-reader ] unit-test
 

core/sequences/sequences-docs.factor

@@ -533,12 +533,18 @@ HELP: concat
 { $description "Concatenates a sequence of sequences together into one sequence. If " { $snippet "seq" } " is empty, outputs " { $snippet "{ }" } ", otherwise the resulting sequence is of the same class as the first element of " { $snippet "seq" } "." }
 { $errors "Throws an error if one of the sequences in " { $snippet "seq" } " contains elements not permitted in sequences of the same class as the first element of " { $snippet "seq" } "." } ;
 
+HELP: concat-as
+{ $values { "seq" sequence } { "exemplar" sequence } { "newseq" sequence } }
+{ $description "Concatenates a sequence of sequences together into one sequence with the same type as " { $snippet "exemplar" } "." }
+{ $errors "Throws an error if one of the sequences in " { $snippet "seq" } " contains elements not permitted in sequences of the same class as " { $snippet "exemplar" } "." } ;
+
 HELP: join
 { $values { "seq" sequence } { "glue" sequence } { "newseq" sequence } }
 { $description "Concatenates a sequence of sequences together into one sequence, placing a copy of " { $snippet "glue" } " between each pair of sequences. The resulting sequence is of the same class as " { $snippet "glue" } "." }
+{ $notes "If the " { $snippet "glue" } " sequence is empty, this word calls " { $link concat-as } "." }
 { $errors "Throws an error if one of the sequences in " { $snippet "seq" } " contains elements not permitted in sequences of the same class as " { $snippet "glue" } "." } ;
 
-{ join concat } related-words
+{ join concat concat-as } related-words
 
 HELP: peek
 { $values { "seq" sequence } { "elt" object } }

core/sequences/sequences.factor

@@ -704,13 +704,14 @@ PRIVATE>
 : sum-lengths ( seq -- n )
     0 [ length + ] reduce ;
 
+: concat-as ( seq exemplar -- newseq )
+    swap [ { } ] [
+        [ sum-lengths over new-resizable ] keep
+        [ over push-all ] each
+    ] if-empty swap like ;
+
 : concat ( seq -- newseq )
-    [ { } ] [
-        [ sum-lengths ] keep
-        [ first new-resizable ] keep
-        [ [ over push-all ] each ] keep
-        first like
-    ] if-empty ;
+    [ { } ] [ dup first concat-as ] if-empty ;
 
 <PRIVATE
 
@@ -720,12 +721,14 @@ PRIVATE>
 PRIVATE>
 
 : join ( seq glue -- newseq )
-    [
-        2dup joined-length over new-resizable [
-            [ [ push-all ] 2curry ] [ [ nip push-all ] 2curry ] 2bi
-            interleave
-        ] keep
-    ] keep like ;
+    dup empty? [ concat-as ] [
+        [
+            2dup joined-length over new-resizable [
+                [ [ push-all ] 2curry ] [ [ nip push-all ] 2curry ] 2bi
+                interleave
+            ] keep
+        ] keep like
+    ] if ;
 
 : padding ( seq n elt quot -- newseq )
     [