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lib.types.defaultTypeMerge: refactor functor.{payload,wrapped} merging

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Johannes Kirschbauer 2024-10-24 11:38:30 +02:00
parent d2dfc1ac21
commit b978799f71
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3 changed files with 60 additions and 14 deletions
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42
lib/types.nix
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@ -83,23 +83,37 @@ rec {
# Default type merging function
# takes two type functors and return the merged type
defaultTypeMerge = f: f':
let wrapped = f.wrapped.typeMerge f'.wrapped.functor;
payload = f.binOp f.payload f'.payload;
let mergedWrapped = f.wrapped.typeMerge f'.wrapped.functor;
mergedPayload = f.binOp f.payload f'.payload;
hasPayload = assert (f'.payload != null) == (f.payload != null); f.payload != null;
hasWrapped = assert (f'.wrapped != null) == (f.wrapped != null); f.wrapped != null;
in
# cannot merge different types
# Abort early: cannot merge different types
if f.name != f'.name
then null
# simple types
else if (f.wrapped == null && f'.wrapped == null)
&& (f.payload == null && f'.payload == null)
then f.type
# composed types
else if (f.wrapped != null && f'.wrapped != null) && (wrapped != null)
then f.type wrapped
# value types
else if (f.payload != null && f'.payload != null) && (payload != null)
then f.type payload
else null;
else
if hasPayload then
if hasWrapped then
# Has both wrapped and payload
throw ''
Type ${f.name} defines both `functor.payload` and `functor.wrapped` at the same time, which is not supported.
Use either `functor.payload` or `functor.wrapped` but not both.
If your code worked before remove `functor.payload` from the type definition.
''
else
# Has payload
if mergedPayload == null then null else f.type mergedPayload
else
if hasWrapped then
# Has wrapped
# TODO(@hsjobeki): This could also be a warning and removed in the future
if mergedWrapped == null then null else f.type mergedWrapped
else
f.type;
# Default type functor
defaultFunctor = name: {