@[test(code_01)]
invar x = 123
x += 1
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Constant or invariable cannot be modified}}
@[test(code_01)]


@[test(code_01)]
invar x = 123
var y = x
y += 100
io.writeln( x, y )
@[test(code_01)]
@[test(code_01)]
123 223
@[test(code_01)]


@[test(code_01)]
routine test100()
{
	invar x = 123
	var y = x
	y += 100
	io.writeln( x, y )
}
test100()
@[test(code_01)]
@[test(code_01)]
123 223
@[test(code_01)]


@[test(code_01)]
var x = 123
invar y = x
x += 1
io.writeln( y )
@[test(code_01)]
@[test(code_01)]
123
@[test(code_01)]


@[test(code_01)]
var x = { 1, 2, 3 }
invar y = x
x.append( 4 )
io.writeln( y )
@[test(code_01)]
@[test(code_01)]
{ 1, 2, 3, 4 }
@[test(code_01)]




@[test(code_01)]
routine f(invar x: @T<list<int>>){}
f( {} )
@[test(code_01)]
@[test(code_01)]
@[test(code_01)]




@[test(code_01)]
routine f(invar x: @T<list<int>>){}
invar ls: list<int> = {};
f(ls)
@[test(code_01)]
@[test(code_01)]
@[test(code_01)]




@[test(code_01)]
var x = { 1, 2, 3 }
invar y = x
y.append( 4 )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid parameter type --- " 'invar<list<int>>' for 'self:list<int>' "}}
@[test(code_01)]



@[test(code_01)]
invar x = { {1, 2}, {3, 4} }
x[0].append( 5 )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid parameter type --- " 'invar<list<int>>' for 'self:list<int>' "}}
@[test(code_01)]



@[test(code_01)]
invar x = { {1, 2}, {3, 4} }
y = x[0]
y.append( 5 )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid parameter type --- " 'invar<list<int>>' for 'self:list<int>' "}}
@[test(code_01)]



@[test(code_01)]
invar x = { {1, 2}, {3, 4} }
var y = x[0]
y.append( 5 )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid assignment from invar value to var varaible}}
@[test(code_01)]



@[test(code_01)]
routine test200()
{
	invar x = { {1, 2}, {3, 4} }
	var y = x[0]
	y.append( 5 )
}
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid assignment from invar value to var varaible}}
@[test(code_01)]



@[test(code_01)]
invar x = { {1, 2}, {3, 4} }
var y = none

y = x[0]
y.append( 5 )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Types not matching --- " 'invar<list<int>>' for 'var<any>' "}}
@[test(code_01)]




@[test(code_01)]
invar x: var<int> = 123
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid declaration}}
@[test(code_01)]



@[test(code_01)]
var x: invar<int> = 123
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid declaration}}
@[test(code_01)]




@[test(code_01)]
var m: map<enum<A,B,C>,int> = { $A -> 1, $B -> 2, $C -> 3 }
invar k = $A
io.writeln( m.find( k ) )
@[test(code_01)]
@[test(code_01)]
( $A(0), 1 )
@[test(code_01)]




@[test(code_01)]
invar m: map<enum<A,B,C>,int> = { $A -> 1, $B -> 2, $C -> 3 }
var k = $A
io.writeln( m.find( k ) )
@[test(code_01)]
@[test(code_01)]
( $A(0), 1 )
@[test(code_01)]



@[test(code_01)]
routine Test( invar par: list<int> )
{
	par.append( 123 )
}
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid parameter type --- " 'invar<list<int>>' for 'self:list<int>' "}}
@[test(code_01)]



@[test(code_01)]
routine Test( invar par: list<int> )
{
	par[0] += 123
}
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Constant or invariable cannot be modified}}
@[test(code_01)]



@[test(code_01)]
routine Test( par: list<int> )
{
	par.append( 123 )
}
invar ls = { 1, 2 }
Test( ls )
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Invalid virtual machine instruction}} .* 
{{Invalid parameter type --- " 'invar<list<int>>' for 'list<int>' "}}
@[test(code_01)]




@[test(code_01)]
type Tuple = tuple<index: invar<int>, name: invar<string>>
tup: Tuple = ( 123, 'abc' )
tup.index = 456
@[test(code_01)]
@[test(code_01)]
{{At line}} .* {{Constant or invariable cannot be modified}}
@[test(code_01)]




@[test(code_01)]
invar a = { 1 }
b = (any) a
b.append( 2 )
io.writeln( std.about(a) != std.about(b) )
@[test(code_01)]
@[test(code_01)]
true
@[test(code_01)]




# Covariant to invariable containers:
@[test(code_01)]
var a = { 1 };
var b = { 1=>2 };
invar c: list<any> = a;
invar d: list<float> = a;
invar e: map<any,any> = b;
@[test(code_01)]
@[test(code_01)]
@[test(code_01)]