GHC.Core.Rules

Functions for collecting together and applying rewrite rules to a module. The CoreRule datatype itself is declared elsewhere.

Looking up rules

lookupRule :: RuleOpts -> InScopeEnv -> (Activation -> Bool) -> Id -> [CoreExpr] -> [CoreRule] -> Maybe (CoreRule, CoreExpr)

The main rule matching function. Attempts to apply all (active) supplied rules to this instance of an application in a given context, returning the rule applied and the resulting expression if successful.

RuleBase, RuleEnv

type RuleBase = NameEnv [CoreRule]

Gathers a collection of CoreRules. Maps (the name of) an Id to its rules

data RuleEnv

A full rule environment which we can apply rules from. Like a RuleBase, but it also includes the set of visible orphans we use to filter out orphan rules which are not visible (even though we can see them...) See Note [Orphans] in GHC.Core

Constructors

RuleEnv

Fields

• re_local_rules :: !RuleBase
• re_home_rules :: !RuleBase
• re_eps_rules :: !RuleBase
• re_visible_orphs :: !ModuleSet

mkRuleEnv :: ModGuts -> RuleBase -> RuleBase -> RuleEnv

emptyRuleEnv :: RuleEnv

updExternalPackageRules :: RuleEnv -> RuleBase -> RuleEnv

addLocalRules :: RuleEnv -> [CoreRule] -> RuleEnv

updLocalRules :: RuleEnv -> [CoreRule] -> RuleEnv

emptyRuleBase :: RuleBase

mkRuleBase :: [CoreRule] -> RuleBase

extendRuleBaseList :: RuleBase -> [CoreRule] -> RuleBase

pprRuleBase :: RuleBase -> SDoc

Checking rule applications

ruleCheckProgram

Arguments

:: RuleOpts

Rule options

-> CompilerPhase

Rule activation test

-> String

Rule pattern

-> (Id -> [CoreRule])

Rules for an Id

-> CoreProgram

Bindings to check in

-> SDoc

Resulting check message

Report partial matches for rules beginning with the specified string for the purposes of error reporting

Manipulating RuleInfo rules

extendRuleInfo :: RuleInfo -> [CoreRule] -> RuleInfo

addRuleInfo :: RuleInfo -> RuleInfo -> RuleInfo

addIdSpecialisations :: Id -> [CoreRule] -> Id

addRulesToId :: RuleBase -> Id -> Id

RuleBase and RuleEnv

Misc. CoreRule helpers

rulesOfBinds :: [CoreBind] -> [CoreRule]

Gather all the rules for locally bound identifiers from the supplied bindings

getRules :: RuleEnv -> Id -> [CoreRule]

pprRulesForUser :: [CoreRule] -> SDoc

Making rules

mkRule :: Module -> Bool -> Bool -> RuleName -> Activation -> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule

Used to make CoreRule for an Id defined in the module being compiled. See also CoreRule

mkSpecRule :: DynFlags -> Module -> Bool -> Activation -> SDoc -> Id -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule

roughTopNames :: [CoreExpr] -> [Maybe Name]

Find the "top" free names of several expressions. Such names are either:

1. The function finally being applied to in an application chain (if that name is a GlobalId: see GHC.Types.Var), or
2. The TyCon if the expression is a Type

This is used for the fast-match-check for rules; if the top names don't match, the rest can't