Re: On adding type information to a dynamically typed language
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- Subject: Re: On adding type information to a dynamically typed language
- From: Gavin Wraith <gavin@...>
- Date: 2017年9月20日 12:06:55 +0100
In message <CABcj=t=jokyccrw18fSEuwVeEDoSPqE7jE-2vWDJOf1UaANv-Q@mail.gmail.com>
Dirk Laurie <dirk.laurie@gmail.com> wrote:
> A patch that makes a parameter list
> (x:number)
> syntactic sugar for
> (x) assert(type(x)=='number')
> would be easy, has anyone done it already?
I sometimes use
the = function (TYPE, VALUE)
assert (type (VALUE) == TYPE)
return VALUE
end
OK, a statement like
f (the ("number", x), the ("string", s))
is more clumsy than f ((x:number), (s:string)).
Another alternative is to do
is = setmetatable ({ }, {
__index = function (_, TYPE)
return function (VALUE)
assert (type (VALUE) == TYPE)
return VALUE
end end })
and use
f (is.number (x), is.string (s))
which looks a lot better, without any patching.
--
Gavin Wraith (gavin@wra1th.plus.com)
Home page: http://www.wra1th.plus.com/