pbackus / expectations Goto Github PK

Hi!
Can you provide more examples about the usage of the whole library?
For example it is not obvious when to prefer Expected!int to Expected!(int, string) or what is the proper usage of andThen and map.

in the dependencies the sumtype library is set to <1.0.0, so the latest releases can't be used with this library.

Dub can't build a project that includes expectations and another library that uses an updated version of sumtype (example below). Do you think you can upgrade expectations to use a newer version of sumtype?

dub.json

{
	"authors": [
		"user"
	],
	"copyright": "Copyright © 2019, user",
	"dependencies": {
		"ddash": "~>0.11.1",
		"expectations": "~>0.2.0"
	},
	"description": "A minimal D application.",
	"license": "proprietary",
	"name": "name"
}

dub build

Unresolvable dependencies to package sumtype:
  ddash:common 0.11.1 depends on sumtype ~>0.8.0
  expectations 0.2.0 depends on sumtype ~>0.6.2

Hi! I have this code:

import expectations;

final class A : Exception
{
    import std.exception : basicExceptionCtors;
    mixin basicExceptionCtors;
}

alias EA = Expected!(string, A);

void main()
{}

When compiling it under dmd v2.084.0, I get this rather cryptic error at compile time:

sumtype.d(1018,4): Error: static assert:  "handler `__lambda1` of type `inout(A) function(inout(A) err) pure nothrow @nogc @safe` never matches"
sumtype.d(838,14):        instantiated from here: `matchImpl!(inout(SumType!(string, A)))`
expectations.d(206,14):        instantiated from here: `tryMatch!(inout(SumType!(string, A)))`
asd.d(9,12):        instantiated from here: `Expected!(string, A)`

The error only seems to happen if the error type is derived from Exception. Replacing mixin basicExceptionCtors; with the exact same constructors as Exception still causes the error.

Is this a bug or am I doing something wrong? Thanks!

Currently it is not possible to use Expected with void:

struct Expected(T, E = Exception)
        if (!is(T == E) && !is(T == void))
/* ... */

This limits the usage of Expected to functions which actually return something. Is there a particular reason for this limitation?