--- /dev/null
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: help.markup help.syntax kernel quotations math sequences
+multiline ;
+IN: combinators.smart
+
+HELP: input<sequence
+{ $values
+ { "quot" quotation }
+ { "newquot" quotation }
+}
+{ $description "Infers the number of inputs, " { $snippet "n" } ", to " { $snippet "quot" } " and calls the " { $snippet "quot" } " with the first " { $snippet "n" } " values from a sequence." }
+{ $examples
+ { $example
+ "USING: combinators.smart math prettyprint ;"
+ "{ 1 2 3 } [ + + ] input<sequence ."
+ "6"
+ }
+} ;
+
+HELP: output>array
+{ $values
+ { "quot" quotation }
+ { "newquot" quotation }
+}
+{ $description "Infers the number or outputs from the quotation and constructs an array from those outputs." }
+{ $examples
+ { $example
+ <" USING: combinators combinators.smart math prettyprint ;
+9 [
+ { [ 1- ] [ 1+ ] [ sq ] } cleave
+] output>array .">
+ "{ 8 10 81 }"
+ }
+} ;
+
+HELP: output>sequence
+{ $values
+ { "quot" quotation } { "exemplar" "an exemplar" }
+ { "newquot" quotation }
+}
+{ $description "Infers the number of outputs from the quotation and constructs a new sequence from those objects of the same type as the exemplar." }
+{ $examples
+ { $example
+ "USING: combinators.smart kernel math prettyprint ;"
+ "4 [ [ 1 + ] [ 2 + ] [ 3 + ] tri ] V{ } output>sequence ."
+ "V{ 5 6 7 }"
+ }
+} ;
+
+HELP: reduce-output
+{ $values
+ { "quot" quotation } { "operation" quotation }
+ { "newquot" quotation }
+}
+{ $description "Infers the number of outputs from " { $snippet "quot" } " and reduces them using " { $snippet "operation" } ". The identity for the " { $link reduce } " operation is the first output." }
+{ $examples
+ { $example
+ "USING: combinators.smart kernel math prettyprint ;"
+ "3 [ [ 4 * ] [ 4 / ] [ 4 - ] tri ] [ * ] reduce-output ."
+ "-9"
+ }
+} ;
+
+HELP: sum-outputs
+{ $values
+ { "quot" quotation }
+ { "n" integer }
+}
+{ $description "Infers the number of outputs from " { $snippet "quot" } " and returns their sum." }
+{ $examples
+ { $example
+ "USING: combinators.smart kernel math prettyprint ;"
+ "10 [ [ 1- ] [ 1+ ] bi ] sum-outputs ."
+ "20"
+ }
+} ;
+
+ARTICLE: "combinators.smart" "Smart combinators"
+"The " { $vocab-link "combinators.smart" } " vocabulary implements " { $emphasis "smart combinators" } ". A smart combinator is one whose behavior depends on the static stack effect of an input quotation." $nl
+"Smart inputs from a sequence:"
+{ $subsection input<sequence }
+"Smart outputs to a sequence:"
+{ $subsection output>sequence }
+{ $subsection output>array }
+"Reducing the output of a quotation:"
+{ $subsection reduce-output }
+"Summing the output of a quotation:"
+{ $subsection sum-outputs } ;
+
+ABOUT: "combinators.smart"
--- /dev/null
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: tools.test combinators.smart math kernel ;
+IN: combinators.smart.tests
+
+: test-bi ( -- 9 11 )
+ 10 [ 1- ] [ 1+ ] bi ;
+
+[ [ test-bi ] output>array ] must-infer
+[ { 9 11 } ] [ [ test-bi ] output>array ] unit-test
+
+[ { 9 11 } [ + ] input<sequence ] must-infer
+[ 20 ] [ { 9 11 } [ + ] input<sequence ] unit-test
+
+
+
+[ 6 ] [ [ 1 2 3 ] [ + ] reduce-output ] unit-test
+
+[ [ 1 2 3 ] [ + ] reduce-output ] must-infer
+
+[ 6 ] [ [ 1 2 3 ] sum-outputs ] unit-test
--- /dev/null
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: accessors fry generalizations kernel macros math.order
+stack-checker math ;
+IN: combinators.smart
+
+MACRO: output>sequence ( quot exemplar -- newquot )
+ [ dup infer out>> ] dip
+ '[ @ _ _ nsequence ] ;
+
+: output>array ( quot -- newquot )
+ { } output>sequence ; inline
+
+MACRO: input<sequence ( quot -- newquot )
+ [ infer in>> ] keep
+ '[ _ firstn @ ] ;
+
+MACRO: reduce-output ( quot operation -- newquot )
+ [ dup infer out>> 1 [-] ] dip n*quot compose ;
+
+: sum-outputs ( quot -- n )
+ [ + ] reduce-output ; inline