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From: "Nasser M. Abbasi" <nma@12000.org>
Newsgroups: comp.lang.ada
Subject: Re: a new language, designed for safety !
Date: Sun, 22 Jun 2014 20:47:59 -0500
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Date: 2014-06-22T20:47:59-05:00
List-Id: <comp.lang.ada>

On 6/22/2014 7:51 PM, Shark8 wrote:

>
> IIRC, Lisp's Error-handling can ensure that types are consistent, even
> though the language itself is dynamically typed.
>

Julia can do that also, and it is dynamically typed. But for Julia
to check at run-time the types are correct, one must supply the type
expected from an operation. I am newbie in Julia, but I find how its
type system works a bit confusing to me:

julia> x=int8(3)  %decalre x to be int8 type
julia> typeof(x)
Int8

julia> y=int64(300000)   %y is int64
julia> typeof(y)
Int64

julia> y=x   %value of x into y
3

julia> typeof(y) %now y type changed to that of x !
Int8

julia> y=int64(300000);  %lets start again
julia> (y=x)::Int64   %but now add assertion

ERROR: type: typeassert: expected Int64, got Int8

julia> y=x  %without assertion, it works, but type conversion happens
3

So in Julia, the run-time will check the type, but the user
must add assertions ::

--Nasser