Commit d61adb3d authored by Committed by Marge Bot
Name (tc)SplitForAll- functions more consistently
There is a zoo of `splitForAll-` functions in `GHC.Core.Type` (as well as `tcSplitForAll-` functions in `GHC.Tc.Utils.TcType`) that all do very similar things, but vary in the particular form of type variable that they return. To make things worse, the names of these functions are often quite misleading. Some particularly egregious examples: * `splitForAllTys` returns `TyCoVar`s, but `splitSomeForAllTys` returns `VarBndr`s. * `splitSomeForAllTys` returns `VarBndr`s, but `tcSplitSomeForAllTys` returns `TyVar`s. * `splitForAllTys` returns `TyCoVar`s, but `splitForAllTysInvis` returns `InvisTVBinder`s. (This in particular arose in the context of #18939, and this finally motivated me to bite the bullet and improve the status quo vis-à-vis how we name these functions.) In an attempt to bring some sanity to how these functions are named, I have opted to rename most of these functions en masse to use consistent suffixes that describe the particular form of type variable that each function returns. In concrete terms, this amounts to: * Functions that return a `TyVar` now use the suffix `-TyVar`. This caused the following functions to be renamed: * `splitTyVarForAllTys` -> `splitForAllTyVars` * `splitForAllTy_ty_maybe` -> `splitForAllTyVar_maybe` * `tcSplitForAllTys` -> `tcSplitForAllTyVars` * `tcSplitSomeForAllTys` -> `tcSplitSomeForAllTyVars` * Functions that return a `CoVar` now use the suffix `-CoVar`. This caused the following functions to be renamed: * `splitForAllTy_co_maybe` -> `splitForAllCoVar_maybe` * Functions that return a `TyCoVar` now use the suffix `-TyCoVar`. This caused the following functions to be renamed: * `splitForAllTy` -> `splitForAllTyCoVar` * `splitForAllTys` -> `splitForAllTyCoVars` * `splitForAllTys'` -> `splitForAllTyCoVars'` * `splitForAllTy_maybe` -> `splitForAllTyCoVar_maybe` * Functions that return a `VarBndr` now use the suffix corresponding to the most relevant type synonym. This caused the following functions to be renamed: * `splitForAllVarBndrs` -> `splitForAllTyCoVarBinders` * `splitForAllTysInvis` -> `splitForAllInvisTVBinders` * `splitForAllTysReq` -> `splitForAllReqTVBinders` * `splitSomeForAllTys` -> `splitSomeForAllTyCoVarBndrs` * `tcSplitForAllVarBndrs` -> `tcSplitForAllTyVarBinders` * `tcSplitForAllTysInvis` -> `tcSplitForAllInvisTVBinders` * `tcSplitForAllTysReq` -> `tcSplitForAllReqTVBinders` * `tcSplitForAllTy_maybe` -> `tcSplitForAllTyVarBinder_maybe` Note that I left the following functions alone: * Functions that split apart things besides `ForAllTy`s, such as `splitFunTys` or `splitPiTys`. Thankfully, there are far fewer of these functions than there are functions that split apart `ForAllTy`s, so there isn't much of a pressing need to apply the new naming convention elsewhere. * Functions that split apart `ForAllCo`s in `Coercion`s, such as `GHC.Core.Coercion.splitForAllCo_maybe`. We could theoretically apply the new naming convention here, but then we'd have to figure out how to disambiguate `Type`-splitting functions from `Coercion`-splitting functions. Ultimately, the `Coercion`-splitting functions aren't used nearly as much as the `Type`-splitting functions, so I decided to leave the former alone. This is purely refactoring and should cause no change in behavior.
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