Created
October 17, 2015 16:30
-
-
Save JakobOvrum/1a19f670e7a3359006af to your computer and use it in GitHub Desktop.
Curry implementation using delegates (inefficient but yields known types)
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import std.traits : isCallable; | |
private auto curryImpl(F, CurriedArgs...)(F f, CurriedArgs curriedArgs) | |
{ | |
import std.traits : ParameterTypeTuple; | |
alias Args = ParameterTypeTuple!F; | |
static if(CurriedArgs.length == Args.length - 1) | |
return (Args[CurriedArgs.length] lastArg) => f(curriedArgs, lastArg); | |
else | |
return (Args[CurriedArgs.length] nextArg) => curryImpl(f, curriedArgs, nextArg); | |
} | |
auto curry(F)(F f) | |
if(isCallable!F) | |
{ | |
import std.traits : ParameterTypeTuple; | |
alias Args = ParameterTypeTuple!F; | |
static if(Args.length <= 1) | |
return f; | |
else | |
return (Args[0] arg) => curryImpl(f, arg); | |
} | |
unittest | |
{ | |
int delegate() nullary = () { return 42; }; | |
assert(curry(nullary)() == 42); | |
int delegate(int) unary = a => a; | |
assert(curry(unary)(42) == 42); | |
int delegate(int, int, int) sum = (a, b, c) => a + b + c; | |
static assert(is(typeof(curry(sum)) == int delegate(int) delegate(int) pure nothrow @safe delegate(int) pure nothrow @safe)); | |
assert(curry(sum)(1)(2)(3) == 6); | |
string delegate(string, int) concat = (str, n) { | |
string result; | |
foreach(immutable i; 0 .. n) | |
result ~= str; | |
return result; | |
}; | |
assert(curry(concat)("foo")(3) == "foofoofoo"); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment