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-rw-r--r--new-luxc/source/luxc/lang/analysis/case.lux312
-rw-r--r--new-luxc/source/luxc/lang/analysis/case/coverage.lux300
2 files changed, 0 insertions, 612 deletions
diff --git a/new-luxc/source/luxc/lang/analysis/case.lux b/new-luxc/source/luxc/lang/analysis/case.lux
deleted file mode 100644
index d9efa2bf4..000000000
--- a/new-luxc/source/luxc/lang/analysis/case.lux
+++ /dev/null
@@ -1,312 +0,0 @@
-(.module:
- lux
- (lux (control [monad #+ do]
- ["ex" exception #+ exception:]
- eq)
- (data [bool]
- [number]
- [product]
- ["e" error]
- [maybe]
- [text]
- text/format
- (coll [list "list/" Fold<List> Monoid<List> Functor<List>]))
- [macro]
- (macro [code])
- (lang [type]
- (type ["tc" check])))
- (luxc ["&" lang]
- (lang ["&." scope]
- ["la" analysis]
- (analysis [".A" common]
- [".A" structure]
- (case [".A" coverage])))))
-
-(do-template [<name>]
- [(exception: #export (<name> {message Text})
- message)]
-
- [Cannot-Match-Type-With-Pattern]
- [Sum-Type-Has-No-Case]
- [Unrecognized-Pattern-Syntax]
- [Cannot-Simplify-Type-For-Pattern-Matching]
- [Cannot-Have-Empty-Branches]
- [Non-Exhaustive-Pattern-Matching]
- [Symbols-Must-Be-Unqualified-Inside-Patterns]
- )
-
-(def: (pattern-error type pattern)
- (-> Type Code Text)
- (format " Type: " (%type type) "\n"
- "Pattern: " (%code pattern)))
-
-(def: (re-quantify envs baseT)
- (-> (List (List Type)) Type Type)
- (case envs
- #.Nil
- baseT
-
- (#.Cons head tail)
- (re-quantify tail (#.UnivQ head baseT))))
-
-## Type-checking on the input value is done during the analysis of a
-## "case" expression, to ensure that the patterns being used make
-## sense for the type of the input value.
-## Sometimes, that input value is complex, by depending on
-## type-variables or quantifications.
-## This function makes it easier for "case" analysis to properly
-## type-check the input with respect to the patterns.
-(def: (simplify-case-type caseT)
- (-> Type (Meta Type))
- (loop [envs (: (List (List Type))
- (list))
- caseT caseT]
- (case caseT
- (#.Var id)
- (do macro.Monad<Meta>
- [?caseT' (&.with-type-env
- (tc.read id))]
- (case ?caseT'
- (#.Some caseT')
- (recur envs caseT')
-
- _
- (&.throw Cannot-Simplify-Type-For-Pattern-Matching (%type caseT))))
-
- (#.Named name unnamedT)
- (recur envs unnamedT)
-
- (#.UnivQ env unquantifiedT)
- (recur (#.Cons env envs) unquantifiedT)
-
- ## (^template [<tag> <instancer>]
- ## (<tag> _)
- ## (do macro.Monad<Meta>
- ## [[_ instanceT] (&.with-type-env
- ## <instancer>)]
- ## (recur (maybe.assume (type.apply (list instanceT) caseT)))))
- ## ([#.UnivQ tc.var]
- ## [#.ExQ tc.existential])
-
- (#.ExQ _)
- (do macro.Monad<Meta>
- [[ex-id exT] (&.with-type-env
- tc.existential)]
- (recur envs (maybe.assume (type.apply (list exT) caseT))))
-
- (#.Apply inputT funcT)
- (case funcT
- (#.Var funcT-id)
- (do macro.Monad<Meta>
- [funcT' (&.with-type-env
- (do tc.Monad<Check>
- [?funct' (tc.read funcT-id)]
- (case ?funct'
- (#.Some funct')
- (wrap funct')
-
- _
- (tc.throw Cannot-Simplify-Type-For-Pattern-Matching (%type caseT)))))]
- (recur envs (#.Apply inputT funcT')))
-
- _
- (case (type.apply (list inputT) funcT)
- (#.Some outputT)
- (recur envs outputT)
-
- #.None
- (&.throw Cannot-Simplify-Type-For-Pattern-Matching (%type caseT))))
-
- (#.Product _)
- (|> caseT
- type.flatten-tuple
- (list/map (re-quantify envs))
- type.tuple
- (:: macro.Monad<Meta> wrap))
-
- _
- (:: macro.Monad<Meta> wrap (re-quantify envs caseT)))))
-
-## This function handles several concerns at once, but it must be that
-## way because those concerns are interleaved when doing
-## pattern-matching and they cannot be separated.
-## The pattern is analysed in order to get a general feel for what is
-## expected of the input value. This, in turn, informs the
-## type-checking of the input.
-## A kind of "continuation" value is passed around which signifies
-## what needs to be done _after_ analysing a pattern.
-## In general, this is done to analyse the "body" expression
-## associated to a particular pattern _in the context of_ said
-## pattern.
-## The reason why *context* is important is because patterns may bind
-## values to local variables, which may in turn be referenced in the
-## body expressions.
-## That is why the body must be analysed in the context of the
-## pattern, and not separately.
-(def: (analyse-pattern num-tags inputT pattern next)
- (All [a] (-> (Maybe Nat) Type Code (Meta a) (Meta [la.Pattern a])))
- (case pattern
- [cursor (#.Symbol ["" name])]
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [outputA (&scope.with-local [name inputT]
- next)
- idx &scope.next-local]
- (wrap [(` ("lux case bind" (~ (code.nat idx)))) outputA])))
-
- [cursor (#.Symbol ident)]
- (&.with-cursor cursor
- (&.throw Symbols-Must-Be-Unqualified-Inside-Patterns (%ident ident)))
-
- (^template [<type> <code-tag>]
- [cursor (<code-tag> test)]
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [_ (&.with-type-env
- (tc.check inputT <type>))
- outputA next]
- (wrap [pattern outputA]))))
- ([Bool #.Bool]
- [Nat #.Nat]
- [Int #.Int]
- [Deg #.Deg]
- [Frac #.Frac]
- [Text #.Text])
-
- (^ [cursor (#.Tuple (list))])
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [_ (&.with-type-env
- (tc.check inputT Top))
- outputA next]
- (wrap [(` ("lux case tuple" [])) outputA])))
-
- (^ [cursor (#.Tuple (list singleton))])
- (analyse-pattern #.None inputT singleton next)
-
- [cursor (#.Tuple sub-patterns)]
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [inputT' (simplify-case-type inputT)]
- (case inputT'
- (#.Product _)
- (let [sub-types (type.flatten-tuple inputT')
- num-sub-types (maybe.default (list.size sub-types)
- num-tags)
- num-sub-patterns (list.size sub-patterns)
- matches (cond (n/< num-sub-types num-sub-patterns)
- (let [[prefix suffix] (list.split (n/dec num-sub-patterns) sub-types)]
- (list.zip2 (list/compose prefix (list (type.tuple suffix))) sub-patterns))
-
- (n/> num-sub-types num-sub-patterns)
- (let [[prefix suffix] (list.split (n/dec num-sub-types) sub-patterns)]
- (list.zip2 sub-types (list/compose prefix (list (code.tuple suffix)))))
-
- ## (n/= num-sub-types num-sub-patterns)
- (list.zip2 sub-types sub-patterns)
- )]
- (do @
- [[memberP+ thenA] (list/fold (: (All [a]
- (-> [Type Code] (Meta [(List la.Pattern) a])
- (Meta [(List la.Pattern) a])))
- (function (_ [memberT memberC] then)
- (do @
- [[memberP [memberP+ thenA]] ((:! (All [a] (-> (Maybe Nat) Type Code (Meta a) (Meta [la.Pattern a])))
- analyse-pattern)
- #.None memberT memberC then)]
- (wrap [(list& memberP memberP+) thenA]))))
- (do @
- [nextA next]
- (wrap [(list) nextA]))
- (list.reverse matches))]
- (wrap [(` ("lux case tuple" [(~+ memberP+)]))
- thenA])))
-
- _
- (&.throw Cannot-Match-Type-With-Pattern (pattern-error inputT pattern))
- )))
-
- [cursor (#.Record record)]
- (do macro.Monad<Meta>
- [record (structureA.normalize record)
- [members recordT] (structureA.order record)
- _ (&.with-type-env
- (tc.check inputT recordT))]
- (analyse-pattern (#.Some (list.size members)) inputT [cursor (#.Tuple members)] next))
-
- [cursor (#.Tag tag)]
- (&.with-cursor cursor
- (analyse-pattern #.None inputT (` ((~ pattern))) next))
-
- (^ [cursor (#.Form (list& [_ (#.Nat idx)] values))])
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [inputT' (simplify-case-type inputT)]
- (case inputT'
- (#.Sum _)
- (let [flat-sum (type.flatten-variant inputT')
- size-sum (list.size flat-sum)
- num-cases (maybe.default size-sum num-tags)]
- (case (list.nth idx flat-sum)
- (^multi (#.Some case-type)
- (n/< num-cases idx))
- (if (and (n/> num-cases size-sum)
- (n/= (n/dec num-cases) idx))
- (do macro.Monad<Meta>
- [[testP nextA] (analyse-pattern #.None
- (type.variant (list.drop (n/dec num-cases) flat-sum))
- (` [(~+ values)])
- next)]
- (wrap [(` ("lux case variant" (~ (code.nat idx)) (~ (code.nat num-cases)) (~ testP)))
- nextA]))
- (do macro.Monad<Meta>
- [[testP nextA] (analyse-pattern #.None case-type (` [(~+ values)]) next)]
- (wrap [(` ("lux case variant" (~ (code.nat idx)) (~ (code.nat num-cases)) (~ testP)))
- nextA])))
-
- _
- (&.throw Sum-Type-Has-No-Case
- (format "Case: " (%n idx) "\n"
- "Type: " (%type inputT)))))
-
- _
- (&.throw Cannot-Match-Type-With-Pattern (pattern-error inputT pattern)))))
-
- (^ [cursor (#.Form (list& [_ (#.Tag tag)] values))])
- (&.with-cursor cursor
- (do macro.Monad<Meta>
- [tag (macro.normalize tag)
- [idx group variantT] (macro.resolve-tag tag)
- _ (&.with-type-env
- (tc.check inputT variantT))]
- (analyse-pattern (#.Some (list.size group)) inputT (` ((~ (code.nat idx)) (~+ values))) next)))
-
- _
- (&.throw Unrecognized-Pattern-Syntax (%code pattern))
- ))
-
-(def: #export (analyse-case analyse inputC branches)
- (-> &.Analyser Code (List [Code Code]) (Meta la.Analysis))
- (case branches
- #.Nil
- (&.throw Cannot-Have-Empty-Branches "")
-
- (#.Cons [patternH bodyH] branchesT)
- (do macro.Monad<Meta>
- [[inputT inputA] (commonA.with-unknown-type
- (analyse inputC))
- outputH (analyse-pattern #.None inputT patternH (analyse bodyH))
- outputT (monad.map @
- (function (_ [patternT bodyT])
- (analyse-pattern #.None inputT patternT (analyse bodyT)))
- branchesT)
- outputHC (|> outputH product.left coverageA.determine)
- outputTC (monad.map @ (|>> product.left coverageA.determine) outputT)
- _ (case (monad.fold e.Monad<Error> coverageA.merge outputHC outputTC)
- (#e.Success coverage)
- (&.assert Non-Exhaustive-Pattern-Matching ""
- (coverageA.exhaustive? coverage))
-
- (#e.Error error)
- (&.fail error))]
- (wrap (` ("lux case" (~ inputA) (~ (code.record (list& outputH outputT)))))))))
diff --git a/new-luxc/source/luxc/lang/analysis/case/coverage.lux b/new-luxc/source/luxc/lang/analysis/case/coverage.lux
deleted file mode 100644
index 38f977011..000000000
--- a/new-luxc/source/luxc/lang/analysis/case/coverage.lux
+++ /dev/null
@@ -1,300 +0,0 @@
-(.module:
- lux
- (lux (control [monad #+ do]
- ["ex" exception #+ exception:]
- eq)
- (data [bool "bool/" Eq<Bool>]
- [number]
- ["e" error "error/" Monad<Error>]
- text/format
- (coll [list "list/" Fold<List>]
- (dictionary ["dict" unordered #+ Dict])))
- [macro "macro/" Monad<Meta>])
- (luxc ["&" lang]
- (lang ["la" analysis])))
-
-(exception: #export (Unknown-Pattern {message Text})
- message)
-
-## The coverage of a pattern-matching expression summarizes how well
-## all the possible values of an input are being covered by the
-## different patterns involved.
-## Ideally, the pattern-matching has "exhaustive" coverage, which just
-## means that every possible value can be matched by at least 1
-## pattern.
-## Every other coverage is considered partial, and it would be valued
-## as insuficient (since it could lead to runtime errors due to values
-## not being handled by any pattern).
-## The #Partial tag covers arbitrary partial coverages in a general
-## way, while the other tags cover more specific cases for booleans
-## and variants.
-(type: #export #rec Coverage
- #Partial
- (#Bool Bool)
- (#Variant Nat (Dict Nat Coverage))
- (#Seq Coverage Coverage)
- (#Alt Coverage Coverage)
- #Exhaustive)
-
-(def: #export (exhaustive? coverage)
- (-> Coverage Bool)
- (case coverage
- (#Exhaustive _)
- true
-
- _
- false))
-
-(def: #export (determine pattern)
- (-> la.Pattern (Meta Coverage))
- (case pattern
- ## Binding amounts to exhaustive coverage because any value can be
- ## matched that way.
- ## Unit [] amounts to exhaustive coverage because there is only one
- ## possible value, so matching against it covers all cases.
- (^or (^code ("lux case bind" (~ _))) (^code ("lux case tuple" [])))
- (macro/wrap #Exhaustive)
-
- (^code ("lux case tuple" [(~ singleton)]))
- (determine singleton)
-
- ## Primitive patterns always have partial coverage because there
- ## are too many possibilities as far as values go.
- (^or [_ (#.Nat _)] [_ (#.Int _)] [_ (#.Deg _)]
- [_ (#.Frac _)] [_ (#.Text _)])
- (macro/wrap #Partial)
-
- ## Bools are the exception, since there is only "true" and
- ## "false", which means it is possible for boolean
- ## pattern-matching to become exhaustive if complementary parts meet.
- [_ (#.Bool value)]
- (macro/wrap (#Bool value))
-
- ## Tuple patterns can be exhaustive if there is exhaustiveness for all of
- ## their sub-patterns.
- (^code ("lux case tuple" [(~+ subs)]))
- (loop [subs subs]
- (case subs
- #.Nil
- (macro/wrap #Exhaustive)
-
- (#.Cons sub subs')
- (do macro.Monad<Meta>
- [pre (determine sub)
- post (recur subs')]
- (if (exhaustive? post)
- (wrap pre)
- (wrap (#Seq pre post))))))
-
- ## Variant patterns can be shown to be exhaustive if all the possible
- ## cases are handled exhaustively.
- (^code ("lux case variant" (~ [_ (#.Nat tag-id)]) (~ [_ (#.Nat num-tags)]) (~ sub)))
- (do macro.Monad<Meta>
- [=sub (determine sub)]
- (wrap (#Variant num-tags
- (|> (dict.new number.Hash<Nat>)
- (dict.put tag-id =sub)))))
-
- _
- (&.throw Unknown-Pattern (%code pattern))))
-
-(def: (xor left right)
- (-> Bool Bool Bool)
- (or (and left (not right))
- (and (not left) right)))
-
-## The coverage checker not only verifies that pattern-matching is
-## exhaustive, but also that there are no redundant patterns.
-## Redundant patterns will never be executed, since there will
-## always be a pattern prior to them that would match the input.
-## Because of that, the presence of redundant patterns is assumed to
-## be a bug, likely due to programmer carelessness.
-(def: redundant-pattern
- (e.Error Coverage)
- (e.fail "Redundant pattern."))
-
-(def: (flatten-alt coverage)
- (-> Coverage (List Coverage))
- (case coverage
- (#Alt left right)
- (list& left (flatten-alt right))
-
- _
- (list coverage)))
-
-(struct: _ (Eq Coverage)
- (def: (= reference sample)
- (case [reference sample]
- [#Exhaustive #Exhaustive]
- true
-
- [(#Bool sideR) (#Bool sideS)]
- (bool/= sideR sideS)
-
- [(#Variant allR casesR) (#Variant allS casesS)]
- (and (n/= allR allS)
- (:: (dict.Eq<Dict> =) = casesR casesS))
-
- [(#Seq leftR rightR) (#Seq leftS rightS)]
- (and (= leftR leftS)
- (= rightR rightS))
-
- [(#Alt _) (#Alt _)]
- (let [flatR (flatten-alt reference)
- flatS (flatten-alt sample)]
- (and (n/= (list.size flatR) (list.size flatS))
- (list.every? (function (_ [coverageR coverageS])
- (= coverageR coverageS))
- (list.zip2 flatR flatS))))
-
- _
- false)))
-
-(open Eq<Coverage> "C/")
-
-## After determining the coverage of each individual pattern, it is
-## necessary to merge them all to figure out if the entire
-## pattern-matching expression is exhaustive and whether it contains
-## redundant patterns.
-(def: #export (merge addition so-far)
- (-> Coverage Coverage (e.Error Coverage))
- (case [addition so-far]
- ## The addition cannot possibly improve the coverage.
- [_ #Exhaustive]
- redundant-pattern
-
- ## The addition completes the coverage.
- [#Exhaustive _]
- (error/wrap #Exhaustive)
-
- [#Partial #Partial]
- (error/wrap #Partial)
-
- ## 2 boolean coverages are exhaustive if they compliment one another.
- (^multi [(#Bool sideA) (#Bool sideSF)]
- (xor sideA sideSF))
- (error/wrap #Exhaustive)
-
- [(#Variant allA casesA) (#Variant allSF casesSF)]
- (cond (not (n/= allSF allA))
- (e.fail "Variants do not match.")
-
- (:: (dict.Eq<Dict> Eq<Coverage>) = casesSF casesA)
- redundant-pattern
-
- ## else
- (do e.Monad<Error>
- [casesM (monad.fold @
- (function (_ [tagA coverageA] casesSF')
- (case (dict.get tagA casesSF')
- (#.Some coverageSF)
- (do @
- [coverageM (merge coverageA coverageSF)]
- (wrap (dict.put tagA coverageM casesSF')))
-
- #.None
- (wrap (dict.put tagA coverageA casesSF'))))
- casesSF (dict.entries casesA))]
- (wrap (if (let [case-coverages (dict.values casesM)]
- (and (n/= allSF (list.size case-coverages))
- (list.every? exhaustive? case-coverages)))
- #Exhaustive
- (#Variant allSF casesM)))))
-
- [(#Seq leftA rightA) (#Seq leftSF rightSF)]
- (case [(C/= leftSF leftA) (C/= rightSF rightA)]
- ## There is nothing the addition adds to the coverage.
- [true true]
- redundant-pattern
-
- ## The 2 sequences cannot possibly be merged.
- [false false]
- (error/wrap (#Alt so-far addition))
-
- ## Same prefix
- [true false]
- (do e.Monad<Error>
- [rightM (merge rightA rightSF)]
- (if (exhaustive? rightM)
- ## If all that follows is exhaustive, then it can be safely dropped
- ## (since only the "left" part would influence whether the
- ## merged coverage is exhaustive or not).
- (wrap leftSF)
- (wrap (#Seq leftSF rightM))))
-
- ## Same suffix
- [false true]
- (do e.Monad<Error>
- [leftM (merge leftA leftSF)]
- (wrap (#Seq leftM rightA))))
-
- ## The left part will always match, so the addition is redundant.
- (^multi [(#Seq left right) single]
- (C/= left single))
- redundant-pattern
-
- ## The right part is not necessary, since it can always match the left.
- (^multi [single (#Seq left right)]
- (C/= left single))
- (error/wrap single)
-
- ## When merging a new coverage against one based on Alt, it may be
- ## that one of the many coverages in the Alt is complementary to
- ## the new one, so effort must be made to fuse carefully, to match
- ## the right coverages together.
- ## If one of the Alt sub-coverages matches the new one, the cycle
- ## must be repeated, in case the resulting coverage can now match
- ## other ones in the original Alt.
- ## This process must be repeated until no further productive
- ## merges can be done.
- [_ (#Alt leftS rightS)]
- (do e.Monad<Error>
- [#let [fuse-once (: (-> Coverage (List Coverage)
- (e.Error [(Maybe Coverage)
- (List Coverage)]))
- (function (_ coverage possibilities)
- (loop [alts possibilities]
- (case alts
- #.Nil
- (wrap [#.None (list coverage)])
-
- (#.Cons alt alts')
- (case (merge coverage alt)
- (#e.Success altM)
- (case altM
- (#Alt _)
- (do @
- [[success alts+] (recur alts')]
- (wrap [success (#.Cons alt alts+)]))
-
- _
- (wrap [(#.Some altM) alts']))
-
- (#e.Error error)
- (e.fail error))
- ))))]
- [success possibilities] (fuse-once addition (flatten-alt so-far))]
- (loop [success success
- possibilities possibilities]
- (case success
- (#.Some coverage')
- (do @
- [[success' possibilities'] (fuse-once coverage' possibilities)]
- (recur success' possibilities'))
-
- #.None
- (case (list.reverse possibilities)
- (#.Cons last prevs)
- (wrap (list/fold (function (_ left right) (#Alt left right))
- last
- prevs))
-
- #.Nil
- (undefined)))))
-
- _
- (if (C/= so-far addition)
- ## The addition cannot possibly improve the coverage.
- redundant-pattern
- ## There are now 2 alternative paths.
- (error/wrap (#Alt so-far addition)))))
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-24 19:23:08 +0000