digitalmars.D.bugs - [Issue 4391] New: std.functional.curry is not a real curry
- d-bugmail puremagic.com (22/22) Jun 25 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4391
- d-bugmail puremagic.com (125/125) Jun 25 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4391
- d-bugmail puremagic.com (10/10) Jan 09 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4391
- d-bugmail puremagic.com (11/11) Jun 09 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4391
- d-bugmail puremagic.com (12/12) Sep 03 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4391
http://d.puremagic.com/issues/show_bug.cgi?id=4391 Summary: std.functional.curry is not a real curry Product: D Version: D2 Platform: Other OS/Version: All Status: NEW Severity: normal Priority: P2 Component: Phobos AssignedTo: nobody puremagic.com ReportedBy: graham.fawcett gmail.com 06:37:50 PDT --- The "curry" template in std.functional is not actually a curry, but a partial application. A curry function should take a single argument, a binary function: (A a, B b) { return ... } and return a nested unary function: (A a) { return (B b) { return ... }; }; -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 25 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4391 Philippe Sigaud <philippe.sigaud gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |philippe.sigaud gmail.com 21:13:39 CEST --- Here is a possible patch: /** Takes a D function, and curries it (in traditional, mathematical sense): given a n-args function, it creates n 1-arg functions nested inside one another. When all original arguments are reached, it returns the result. Example: ---- int add(int i, int j) { return i+j;} alias curry!add cadd; // cadd waits for an int, will return an int delegate(int) auto add3 = cadd(3); // add3 is a function that take an int and return this int + 3. auto m = map!add3([0,1,2,3]); assert(equal(m, [3,4,5,6])); bool equals(int i, int j) { return i==j;} alias curry!equals cequals; auto equals4 = cequals(4); // equals4 is a function taking an int and return true iff this int is 4. auto f = filter!equals4([2,3,4,5,4,3,2,2,3,4]); assert(equal(f, [4,4,4])); ---- What's fun is that it'll work for template functions too. Example: ---- string conj(A, B)(A a, B b) { return to!string(a)~to!string(b); } alias curry!conj cconj; auto c1 = cconj(1); // c1 is a template function waiting for any type. assert(c1('a') == "1a"); ---- BUG: for now, it does not verify the compatibility of types while you give it the arguments. It's only at the end that it sees whether or not it can call the function with these arguments. Example: ---- // given a function like this, with dependencies between the arguments' types: A foo(A,B,C)(A a, Tuple!(B,A) b, Tuple!(C,B,A) c) { return a+b.field[1]+c.field[2];} // if you curries it and gives it an int as first argument, the returned template function should really be: int foo2(B,C)(Tuple!(B,int) b) { return anotherFunction;} // because we now know A to be an int... ---- */ template curry(alias fun) { static if (isFunction!fun) enum curry = mixin(curryImpl!(fun, "", ParameterTypeTuple!fun)); else enum curry = curriedFunction!(fun)(); } template curryImpl(alias fun, string xs, T...) { static if (T.length == 0) enum curryImpl = "&fun"; else static if (T.length == 1) enum curryImpl = "(" ~ T[0].stringof ~ " x1) { return fun(" ~ xs ~ "x1);}"; else enum curryImpl = "(" ~ T[0].stringof ~ " x" ~ to!string(T.length) ~ ") { return " ~ curryImpl!(fun,xs ~ "x" ~ to!string(T.length) ~ ", ", T[1..$]) ~ ";}"; } struct CurriedFunction(alias fun, T...) /+if (T.length)+/ { T _t; static if (T.length) void initialize(T t) { _t = t;} template OpCallType(U...) { static if (is (typeof(fun(Init!T, Init!U)))) alias typeof(fun(Init!T, Init!U)) OpCallType; else alias CurriedFunction!(fun, T, U) OpCallType; } OpCallType!U opCall(U...)(U u) { static if(is(typeof(fun(_t, u)))) return fun(_t,u); else { CurriedFunction!(fun, T, U) cf; static if (U.length) cf.initialize(_t, u); return cf; } } } CurriedFunction!(fun, TypeTuple!()) curriedFunction(alias fun)() { CurriedFunction!(fun, TypeTuple!()) cf; return cf; } unittest { int add(int i, int j) { return i+j;} alias curry!add cadd; // cadd waits for an int, will return an int delegate(int) auto add3 = cadd(3); // add3 is a function that take an int and return this int + 3. auto m = map!add3([0,1,2,3]); assert(equal(m, [3,4,5,6])); bool equals(int i, int j) { return i==j;} alias curry!equals cequals; auto equals4 = cequals(4); // equals4 is a function taking an int and return true iff this int is 4. auto f = filter!equals4([2,3,4,5,4,3,2,2,3,4]); assert(equal(f, [4,4,4])); } So, the template function part is still a bit rough. I've plan to keep track of types dependencies, but ... well, Real Life (tm) is in the way. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 25 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4391 Andrei Alexandrescu <andrei metalanguage.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |ASSIGNED CC| |andrei metalanguage.com AssignedTo|nobody puremagic.com |andrei metalanguage.com -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jan 09 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4391 timon.gehr gmx.ch changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |timon.gehr gmx.ch I suggest to also keep the current implementation of "curry", but to rename it to "partial". -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 09 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4391 klickverbot <code klickverbot.at> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |code klickverbot.at --- Timon: Agreed, having a »curry« that really performs partial application is quite confusing (and gets us into trouble if we want to add a real curry), this has been on my todo list for quite some time now. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 03 2011