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(.module:
[lux #*
[abstract ["." monad (#+ do)]]
[data
text/format
["." name ("#@." equivalence)]]
["r" math/random (#+ Random) ("#@." monad)]
["_" test (#+ Test)]
[control
pipe]
[data
["." product]
["." maybe]
["." text ("#@." equivalence)]
[collection
["." list ("#@." monad)]
["." set]]]
["." type
["." check]]
[macro
["." code]]]
[//
["_." primitive]
["_." structure]]
{1
["." /
["/#" //
["#." module]
["#." type]
["/#" //
["/#" //
["#." analysis (#+ Analysis Variant Tag Operation)]]]]]})
(def: (exhaustive-weaving branchings)
(-> (List (List Code)) (List (List Code)))
(case branchings
#.Nil
#.Nil
(#.Cons head+ #.Nil)
(list@map (|>> list) head+)
(#.Cons head+ tail++)
(do list.monad
[tail+ (exhaustive-weaving tail++)
head head+]
(wrap (#.Cons head tail+)))))
(def: #export (exhaustive-branches allow-literals? variantTC inputC)
(-> Bit (List [Code Code]) Code (Random (List Code)))
(case inputC
[_ (#.Bit _)]
(r@wrap (list (' #0) (' #1)))
(^template [<tag> <gen> <wrapper>]
[_ (<tag> _)]
(if allow-literals?
(do r.monad
[?sample (r.maybe <gen>)]
(case ?sample
(#.Some sample)
(do @
[else (exhaustive-branches allow-literals? variantTC inputC)]
(wrap (list& (<wrapper> sample) else)))
#.None
(wrap (list (' _)))))
(r@wrap (list (' _)))))
([#.Nat r.nat code.nat]
[#.Int r.int code.int]
[#.Rev r.rev code.rev]
[#.Frac r.frac code.frac]
[#.Text (r.unicode 5) code.text])
(^ [_ (#.Tuple (list))])
(r@wrap (list (' [])))
[_ (#.Tuple members)]
(do r.monad
[member-wise-patterns (monad.map @ (exhaustive-branches allow-literals? variantTC) members)]
(wrap (|> member-wise-patterns
exhaustive-weaving
(list@map code.tuple))))
(^ [_ (#.Record (list))])
(r@wrap (list (' {})))
[_ (#.Record kvs)]
(do r.monad
[#let [ks (list@map product.left kvs)
vs (list@map product.right kvs)]
member-wise-patterns (monad.map @ (exhaustive-branches allow-literals? variantTC) vs)]
(wrap (|> member-wise-patterns
exhaustive-weaving
(list@map (|>> (list.zip2 ks) code.record)))))
(^ [_ (#.Form (list [_ (#.Tag _)] _))])
(do r.monad
[bundles (monad.map @
(function (_ [_tag _code])
(do @
[v-branches (exhaustive-branches allow-literals? variantTC _code)]
(wrap (list@map (function (_ pattern) (` ((~ _tag) (~ pattern))))
v-branches))))
variantTC)]
(wrap (list@join bundles)))
_
(r@wrap (list))
))
(def: #export (input variant-tags record-tags primitivesC)
(-> (List Code) (List Code) (List Code) (Random Code))
(r.rec
(function (_ input)
($_ r.either
(r@map product.right _primitive.primitive)
(do r.monad
[choice (|> r.nat (:: @ map (n/% (list.size variant-tags))))
#let [choiceT (maybe.assume (list.nth choice variant-tags))
choiceC (maybe.assume (list.nth choice primitivesC))]]
(wrap (` ((~ choiceT) (~ choiceC)))))
(do r.monad
[size (|> r.nat (:: @ map (n/% 3)))
elems (r.list size input)]
(wrap (code.tuple elems)))
(r@wrap (code.record (list.zip2 record-tags primitivesC)))
))))
(def: (branch body pattern)
(-> Code Code [Code Code])
[pattern body])
(def: #export test
(<| (_.context (name.module (name-of /._)))
(do r.monad
[module-name (r.unicode 5)
variant-name (r.unicode 5)
record-name (|> (r.unicode 5) (r.filter (|>> (text@= variant-name) not)))
size (|> r.nat (:: @ map (|>> (n/% 10) (n/max 2))))
variant-tags (|> (r.set text.hash size (r.unicode 5)) (:: @ map set.to-list))
record-tags (|> (r.set text.hash size (r.unicode 5)) (:: @ map set.to-list))
primitivesTC (r.list size _primitive.primitive)
#let [primitivesT (list@map product.left primitivesTC)
primitivesC (list@map product.right primitivesTC)
code-tag (|>> [module-name] code.tag)
variant-tags+ (list@map code-tag variant-tags)
record-tags+ (list@map code-tag record-tags)
variantTC (list.zip2 variant-tags+ primitivesC)]
inputC (input variant-tags+ record-tags+ primitivesC)
[outputT outputC] (r.filter (|>> product.left (is? Any) not)
_primitive.primitive)
#let [analyse-pm (|>> (/.case _primitive.phase inputC)
(//type.with-type outputT)
////analysis.with-scope
(do ///.monad
[_ (//module.declare-tags variant-tags false
(#.Named [module-name variant-name]
(type.variant primitivesT)))
_ (//module.declare-tags record-tags false
(#.Named [module-name record-name]
(type.tuple primitivesT)))])
(//module.with-module 0 module-name))]
exhaustive-patterns (exhaustive-branches true variantTC inputC)
#let [exhaustive-branchesC (list@map (branch outputC)
exhaustive-patterns)]]
($_ _.and
(_.test "Will reject empty pattern-matching (no branches)."
(|> (analyse-pm (list))
_structure.check-fails))
(_.test "Can analyse exhaustive pattern-matching."
(|> (analyse-pm exhaustive-branchesC)
_structure.check-succeeds))
(let [non-exhaustive-branchesC (list.take (dec (list.size exhaustive-branchesC))
exhaustive-branchesC)]
(_.test "Will reject non-exhaustive pattern-matching."
(|> (analyse-pm non-exhaustive-branchesC)
_structure.check-fails)))
(do @
[redundant-patterns (exhaustive-branches false variantTC inputC)
redundancy-idx (|> r.nat (:: @ map (n/% (list.size redundant-patterns))))
#let [redundant-branchesC (<| (list@map (branch outputC))
list.concat
(list (list.take redundancy-idx redundant-patterns)
(list (maybe.assume (list.nth redundancy-idx redundant-patterns)))
(list.drop redundancy-idx redundant-patterns)))]]
(_.test "Will reject redundant pattern-matching."
(|> (analyse-pm redundant-branchesC)
_structure.check-fails)))
(do @
[[heterogeneousT heterogeneousC] (r.filter (|>> product.left (check.checks? outputT) not)
_primitive.primitive)
heterogeneous-idx (|> r.nat (:: @ map (n/% (list.size exhaustive-patterns))))
#let [heterogeneous-branchesC (list.concat (list (list.take heterogeneous-idx exhaustive-branchesC)
(list (let [[_pattern _body] (maybe.assume (list.nth heterogeneous-idx exhaustive-branchesC))]
[_pattern heterogeneousC]))
(list.drop (inc heterogeneous-idx) exhaustive-branchesC)))]]
(_.test "Will reject pattern-matching if the bodies of the branches do not all have the same type."
(|> (analyse-pm heterogeneous-branchesC)
_structure.check-fails)))
))))
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