Add each-line combinator

core/io/io-docs.factor

@@ -253,6 +253,10 @@ HELP: lines
 { $values { "stream" "an input stream" } { "seq" "a sequence of strings" } }
 { $description "Reads lines of text until the stream is exhausted, collecting them in a sequence of strings." } ;
 
+HELP: each-line
+{ $values { "quot" { $quotation "( str -- )" } } }
+{ $description "Calls the quotatin with successive lines of text, until the current " { $link input-stream } " is exhausted." } ;
+
 HELP: contents
 { $values { "stream" "an input stream" } { "str" string } }
 { $description "Reads the entire contents of a stream into a string." }
@@ -364,6 +368,8 @@ ARTICLE: "stream-utils" "Stream utilities"
 $nl
 "First, a simple composition of " { $link stream-write } " and " { $link stream-nl } ":"
 { $subsection stream-print }
+"Processing lines one by one:"
+{ $subsection each-line }
 "Sluring an entire stream into memory all at once:"
 { $subsection lines }
 { $subsection contents }

core/io/io.factor

@@ -99,6 +99,9 @@ SYMBOL: error-stream
 : lines ( stream -- seq )
     [ [ readln dup ] [ ] [ drop ] produce ] with-input-stream ;
 
+: each-line ( quot -- )
+    [ [ readln dup ] ] dip [ drop ] while ; inline
+
 : contents ( stream -- str )
     [
         [ 65536 read dup ] [ ] [ drop ] produce concat f like