Generics #6
Description
As a follow up to #3, from @Robbepop: #3 (comment). Should be included in a 0.1 release.
Seeing this we still have the problem that our encoding is not generics-aware which it should imo. So we end up having a different type definition for each Option<T> with a different T instead of re-using the one generic definition. I have made some thoughts about this and came to the conclusion that it should even be fairly simple to actually implement this with some additional built-ins.
There are actually 2 ways we could implement this:
By introducing two new built-in type classes generic_type and generic_param:
{
"strings": {
"Option", # ID 1
"Some", # ID 2
"None", # ID 3
"T", # ID 4
"Foo", # ID 5
"Bar", # ID 6
"Baz", # ID 7
}
"types": {
{ # ID 1
"variant": {
"path" [ 1 ],
"params": [ 4 ]
"variants": [
{
"name": [ 2 ],
"type": [ 2 ],
},
{
"name": [ 3 ],
}
],
}
},
{ # ID 2
# Generic parameter with name `"T"`.
"generic_param": {
"name": 4
}
},
{ # ID 3
"primitive": "u32"
},
{ # ID 4
"primitive": "bool"
},
{ # ID 5
# Forwards to the `Option<u32>` type.
"generic_type": {
"type": 1,
"params": 3,
}
},
{ # ID 6
# Demonstrates usage of a type that contains a Option<u32> type.
"composite": {
"path": [ 5 ],
"fields": [
{
"type": 5
}
],
}
},
{ # ID 7
# Forwards to the `Option<bool>` type.
"generic_type": {
"type": 1,
"params": 4,
}
},
{ # ID 8
# Demonstrates usage of a type that contains a Option<bool> type.
"composite": {
"path": [ 6 ],
"fields": [
{
"type": 7
}
],
}
},
{ # ID 9
# Demonstrates usage of a non-generic type.
"composite": {
"path": [ 7 ],
"field": [
{
"type": 3,
},
{
"type": 4,
},
]
}
}
}
}
By introducing flags for all type fields:
{
"strings": {
"Option", # ID 1
"Some", # ID 2
"None", # ID 3
"T", # ID 4
"Foo", # ID 5
"Bar", # ID 6
"Baz", # ID 7
}
"types": {
{ # ID 1
"variant": {
"path" [ 1 ],
"params": [ 4 ]
"variants": [
{
"name": [ 2 ],
"type": [
{
# 4 indexes into the string table and must have
# the same index as one of the identifier in `params`.
"parameter": 4
}
],
},
{
"name": [ 3 ],
}
],
}
},
{ # ID 3
"primitive": "u32"
},
{ # ID 4
"primitive": "bool"
},
{ # ID 5
# Demonstrates usage of a type that contains a Option<u32> type.
"composite": {
"path": [ 5 ],
"fields": [
{
# Demonstrates usage of the generic type at index 1 (`Option<T>`)
# with a parameter of 4 where 4 indexes into the type table as `u32`.
"type": {
"generic": {
"type": 1,
"params": [ 3 ],
},
}
}
],
}
},
{ # ID 6
# Demonstrates usage of a type that contains a Option<bool> type.
"composite": {
"path": [ 6 ],
"fields": [
{
"type": {
# Demonstrates usage of the generic type at index 1 (`Option<T>`)
# with a parameter of 4 where 4 indexes into the type table as `bool`.
"generic": {
"type": 1,
"params": [ 4 ],
},
}
}
],
}
},
{ # ID 7
# Demonstrates usage of a non-generic type.
"composite": {
"path": [ 7 ],
"field": [
{
"type": {
# 3 indexes into the type table and refers to a non
# generic (aka concrete) type, in this case `u32`.
"concrete": 3
},
},
{
"type": {
# 4 indexes into the type table and refers to a non
# generic (aka concrete) type, in this case `bool`.
"concrete": 4
}
},
]
}
}
}
}