Macro type-checking: support arithmetic conversions #299
+2,335
−1,717
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This commit generalises macro type-checking, making class constraints
more general by allowing what GHC calls FlexibleContexts and
FlexibleInstances.
Key changes:
- A special monad for solving, TcSolveM.
This monad keeps track of a work list and a set of
inert (= fully processed) constraints.
- Solving a constraint using a top-level instance may now add
additional constraints to the work list.
- Instances are keyed using a TrieMap, similar to GHC's RoughMap,
which avoids traversing all instances when doing instance matching.
The solver didn't handle equalities properly, as it didn't account for the result of unification. Now, we try to unify, and if the unifier makes no progress we make the constraint into an inert constraint.
sheaf
changed the title
This commit generalises macro typechecking to take into account C arithmetic conversion rules, e.g. in an operation such as a + b the values 'a' and 'b' are allowed to have different types, with implicit conversions being inserted. For example: - a :: CFloat, b :: CInt => convert b to CFloat before adding - a :: Int, b :: UInt => convert a to UInt before adding
sheaf
force-pushed
the
tc-macro-conversions
branch
from
29b2eca
to
7ea2449
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Builds on top of #296.
This PR generalises macro typechecking to take into account C
arithmetic conversion rules, e.g. in an operation such as
the values
aandbare allowed to have different types, withimplicit conversions being inserted. For example:
a :: CFloat,b :: CInt=> convertbtoCFloatbefore addinga :: Int,b :: UInt=> convertatoUIntbefore addingThe main challenge was to generalise the defaulting infrastructure to allow defaulting a multi-parameter class constraint such as
Add alpha[tau] beta[tau]with the equalityalpha ~ beta.