📄 list-xprod.mldoc
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<!-- list-xprod.mldoc --><!-- Entities.sgml entry <!ENTITY ListXProd SDATA "list-xprod-sig.sml"> --><!DOCTYPE ML-DOC SYSTEM><COPYRIGHT OWNER="Bell Labs, Lucent Technologies" YEAR=1998><VERSION VERID="1.0" YEAR=1998 MONTH=6 DAY=11><TITLE>The ListXProd structure</TITLE><INTERFACE><HEAD>The <CD/ListXProd/ structure</HEAD><SEEALSO> <STRREF TOPID DOCUMENT=SML-BASIS-DOC/List/ <STRREF TOPID DOCUMENT=SML-BASIS-DOC/ListPair/</SEEALSO><PP>The <STRREF NOLINK/ListXProd/ structure provides functions forcomputing with the cross product of two lists. For purposes ofdocumentation, we define the cross product of two lists as thethe list produced by the following function:<CODE>fun xProd (l1, l2) = let fun mkPair a b = (a,b) in List.foldr (fn (a,l) => (map (mkPair a) l2)@l) [] l1 end</CODE><STRUCTURE STRID="ListXProd"> <SIGBODY SIGID="LIST_XPROD" FILE=LIST-XPROD> <SPEC> <VAL>appX<TY>(('a * 'b) -> 'c) -> ('a list * 'b list) -> unit <COMMENT> <PROTOTY> appX <ARG/f/ (<ARG/l1/, <ARG/l2/) </PROTOTY> applies <ARG/f/ to the cross product of the two lists. This is equivalent to: <CODE> List.app f (xProd(l1,l2)) </CODE> <SPEC> <VAL>mapX<TY>(('a * 'b) -> 'c) -> ('a list * 'b list) -> 'c list <COMMENT> <PROTOTY> mapX <ARG/f/ (<ARG/l/, <ARG/l2/) </PROTOTY> creates a new list by mapping <ARG/f/ across the cross product of the two lists. This is equivalent to: <CODE> List.map f (xProd(l1,l2)) </CODE> <SPEC> <VAL>foldX<TY>(('a * 'b * 'c) -> 'c) -> ('a list * 'b list) -> 'c -> 'c <COMMENT> <PROTOTY> foldX <ARG/f/ (<ARG/l/, <ARG/l2/) <ARG/a/ </PROTOTY> fold <ARG/f/ across the cross product of the two lists. This is equivalent to: <CODE> List.foldl (fn((a,b),c) => f(a,b,c)) a (xProd(l1,l2)) </CODE></STRUCTURE></INTERFACE>⌨️ 快捷键说明
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