Skip to content

fix: array-literal pattern binders read 1-based Lua indices #69

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
Unisay merged 1 commit into from
Jun 14, 2026
Merged

fix: array-literal pattern binders read 1-based Lua indices #69

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 4 additions & 3 deletions lib/Language/PureScript/Backend/Lua.hs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,3 @@
{-# LANGUAGE QuasiQuotes #-}

module Language.PureScript.Backend.Lua
( fromUberModule
, fromIR
Expand Down Expand Up @@ -177,7 +175,10 @@ fromIR foreigns topLevelNames modname ir = case ir of
IR.ArrayLength _ann e →
Right . Lua.hash <$> goExp e
IR.ArrayIndex _ann expr index →
Right . flip Lua.varIndex (Lua.Integer (fromIntegral index)) <$> goExp expr
-- IR array indices are 0-based (de Bruijn-style, like the source language),
-- but Lua tables are 1-based, so shift by one. This mirrors the arrays FFI
-- `indexImpl`, which reads `xs[i + 1]`. See issue #49.
Right . flip Lua.varIndex (Lua.Integer (fromIntegral index + 1)) <$> goExp expr
IR.ObjectProp _ann expr propName →
Right . flip Lua.varField (fromPropName propName) <$> goExp expr
IR.ObjectUpdate _ann expr propValues → do
Expand Down
26 changes: 26 additions & 0 deletions test/ps/golden/Golden/ArrayPatternMatch/Test.purs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
module Golden.ArrayPatternMatch.Test where

import Prelude

import Effect (Effect)
import Effect.Console (logShow)

-- Matching an array-literal pattern destructures by index. The binders must
-- read 1-based Lua slots; the regression in #49 read them 0-based, so the
-- first element came back nil and the match crashed at runtime.
firstTwo :: Array Int -> Int
firstTwo = case _ of
[ a, b ] -> a + b
_ -> -1

lastOfThree :: Array Int -> Int
lastOfThree = case _ of
[ _, _, c ] -> c
_ -> -1

main :: Effect Unit
main = do
logShow (firstTwo [ 10, 20 ])
logShow (firstTwo [ 1, 2, 3 ])
logShow (firstTwo [])
logShow (lastOfThree [ 7, 8, 9 ])
1 change: 1 addition & 0 deletions test/ps/output/Golden.ArrayPatternMatch.Test/corefn.json
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
{"builtWith":"0.15.16","comments":[],"decls":[{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"bindType":"NonRec","expression":{"abstraction":{"annotation":{"meta":{"metaType":"IsForeign"},"sourceSpan":{"end":[19,10],"start":[19,8]}},"type":"Var","value":{"identifier":"negate","moduleName":["Data","Ring"]}},"annotation":{"meta":{"metaType":"IsSyntheticApp"},"sourceSpan":{"end":[19,10],"start":[19,8]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"ringInt","moduleName":["Data","Ring"]}},"type":"App"},"identifier":"negate"},{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"bindType":"NonRec","expression":{"abstraction":{"annotation":{"meta":{"metaType":"IsForeign"},"sourceSpan":{"end":[13,18],"start":[13,17]}},"type":"Var","value":{"identifier":"add","moduleName":["Data","Semiring"]}},"annotation":{"meta":{"metaType":"IsSyntheticApp"},"sourceSpan":{"end":[13,20],"start":[13,15]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"semiringInt","moduleName":["Data","Semiring"]}},"type":"App"},"identifier":"add"},{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"bindType":"NonRec","expression":{"abstraction":{"abstraction":{"annotation":{"meta":{"metaType":"IsForeign"},"sourceSpan":{"end":[23,32],"start":[23,3]}},"type":"Var","value":{"identifier":"discard","moduleName":["Control","Bind"]}},"annotation":{"meta":{"metaType":"IsSyntheticApp"},"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"discardUnit","moduleName":["Control","Bind"]}},"type":"App"},"annotation":{"meta":{"metaType":"IsSyntheticApp"},"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"bindEffect","moduleName":["Effect"]}},"type":"App"},"identifier":"discard"},{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"bindType":"NonRec","expression":{"abstraction":{"annotation":{"meta":{"metaType":"IsForeign"},"sourceSpan":{"end":[23,10],"start":[23,3]}},"type":"Var","value":{"identifier":"logShow","moduleName":["Effect","Console"]}},"annotation":{"meta":{"metaType":"IsSyntheticApp"},"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"showInt","moduleName":["Data","Show"]}},"type":"App"},"identifier":"logShow"},{"annotation":{"meta":null,"sourceSpan":{"end":[16,32],"start":[16,1]}},"bindType":"NonRec","expression":{"annotation":{"meta":null,"sourceSpan":{"end":[19,10],"start":[17,15]}},"argument":"v","body":{"annotation":{"meta":null,"sourceSpan":{"end":[19,10],"start":[17,15]}},"caseAlternatives":[{"binders":[{"annotation":{"meta":null,"sourceSpan":{"end":[18,14],"start":[18,3]}},"binderType":"LiteralBinder","literal":{"literalType":"ArrayLiteral","value":[{"annotation":{"meta":null,"sourceSpan":{"end":[18,6],"start":[18,5]}},"binderType":"NullBinder"},{"annotation":{"meta":null,"sourceSpan":{"end":[18,9],"start":[18,8]}},"binderType":"NullBinder"},{"annotation":{"meta":null,"sourceSpan":{"end":[18,12],"start":[18,11]}},"binderType":"VarBinder","identifier":"c"}]}}],"expression":{"annotation":{"meta":null,"sourceSpan":{"end":[18,19],"start":[18,18]}},"type":"Var","value":{"identifier":"c","sourcePos":[18,11]}},"isGuarded":false},{"binders":[{"annotation":{"meta":null,"sourceSpan":{"end":[19,4],"start":[19,3]}},"binderType":"NullBinder"}],"expression":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"negate","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[19,10],"start":[19,8]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[19,10],"start":[19,9]}},"type":"Literal","value":{"literalType":"IntLiteral","value":1}},"type":"App"},"isGuarded":false}],"caseExpressions":[{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"v","sourcePos":[0,0]}}],"type":"Case"},"type":"Abs"},"identifier":"lastOfThree"},{"annotation":{"meta":null,"sourceSpan":{"end":[11,29],"start":[11,1]}},"bindType":"NonRec","expression":{"annotation":{"meta":null,"sourceSpan":{"end":[14,10],"start":[12,12]}},"argument":"v","body":{"annotation":{"meta":null,"sourceSpan":{"end":[14,10],"start":[12,12]}},"caseAlternatives":[{"binders":[{"annotation":{"meta":null,"sourceSpan":{"end":[13,11],"start":[13,3]}},"binderType":"LiteralBinder","literal":{"literalType":"ArrayLiteral","value":[{"annotation":{"meta":null,"sourceSpan":{"end":[13,6],"start":[13,5]}},"binderType":"VarBinder","identifier":"a"},{"annotation":{"meta":null,"sourceSpan":{"end":[13,9],"start":[13,8]}},"binderType":"VarBinder","identifier":"b"}]}}],"expression":{"abstraction":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"add","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[13,20],"start":[13,15]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[13,16],"start":[13,15]}},"type":"Var","value":{"identifier":"a","sourcePos":[13,5]}},"type":"App"},"annotation":{"meta":null,"sourceSpan":{"end":[13,20],"start":[13,15]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[13,20],"start":[13,19]}},"type":"Var","value":{"identifier":"b","sourcePos":[13,8]}},"type":"App"},"isGuarded":false},{"binders":[{"annotation":{"meta":null,"sourceSpan":{"end":[14,4],"start":[14,3]}},"binderType":"NullBinder"}],"expression":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"negate","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[14,10],"start":[14,8]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[14,10],"start":[14,9]}},"type":"Literal","value":{"literalType":"IntLiteral","value":1}},"type":"App"},"isGuarded":false}],"caseExpressions":[{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"v","sourcePos":[0,0]}}],"type":"Case"},"type":"Abs"},"identifier":"firstTwo"},{"annotation":{"meta":null,"sourceSpan":{"end":[21,20],"start":[21,1]}},"bindType":"NonRec","expression":{"abstraction":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"discard","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"logShow","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[23,20],"start":[23,12]}},"type":"Var","value":{"identifier":"firstTwo","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[23,31],"start":[23,12]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[23,31],"start":[23,21]}},"type":"Literal","value":{"literalType":"ArrayLiteral","value":[{"annotation":{"meta":null,"sourceSpan":{"end":[23,25],"start":[23,23]}},"type":"Literal","value":{"literalType":"IntLiteral","value":10}},{"annotation":{"meta":null,"sourceSpan":{"end":[23,29],"start":[23,27]}},"type":"Literal","value":{"literalType":"IntLiteral","value":20}}]}},"type":"App"},"type":"App"},"type":"App"},"annotation":{"meta":null,"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[23,32],"start":[23,3]}},"argument":"$__unused","body":{"abstraction":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"discard","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[24,33],"start":[24,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"logShow","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[24,33],"start":[24,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[24,20],"start":[24,12]}},"type":"Var","value":{"identifier":"firstTwo","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[24,32],"start":[24,12]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[24,32],"start":[24,21]}},"type":"Literal","value":{"literalType":"ArrayLiteral","value":[{"annotation":{"meta":null,"sourceSpan":{"end":[24,24],"start":[24,23]}},"type":"Literal","value":{"literalType":"IntLiteral","value":1}},{"annotation":{"meta":null,"sourceSpan":{"end":[24,27],"start":[24,26]}},"type":"Literal","value":{"literalType":"IntLiteral","value":2}},{"annotation":{"meta":null,"sourceSpan":{"end":[24,30],"start":[24,29]}},"type":"Literal","value":{"literalType":"IntLiteral","value":3}}]}},"type":"App"},"type":"App"},"type":"App"},"annotation":{"meta":null,"sourceSpan":{"end":[24,33],"start":[24,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[24,33],"start":[24,3]}},"argument":"$__unused","body":{"abstraction":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"discard","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[25,24],"start":[25,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"logShow","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[25,24],"start":[25,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[25,20],"start":[25,12]}},"type":"Var","value":{"identifier":"firstTwo","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[25,23],"start":[25,12]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[25,23],"start":[25,21]}},"type":"Literal","value":{"literalType":"ArrayLiteral","value":[]}},"type":"App"},"type":"App"},"type":"App"},"annotation":{"meta":null,"sourceSpan":{"end":[25,24],"start":[25,3]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[25,24],"start":[25,3]}},"argument":"$__unused","body":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[0,0],"start":[0,0]}},"type":"Var","value":{"identifier":"logShow","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[26,3]}},"argument":{"abstraction":{"annotation":{"meta":null,"sourceSpan":{"end":[26,23],"start":[26,12]}},"type":"Var","value":{"identifier":"lastOfThree","moduleName":["Golden","ArrayPatternMatch","Test"]}},"annotation":{"meta":null,"sourceSpan":{"end":[26,35],"start":[26,12]}},"argument":{"annotation":{"meta":null,"sourceSpan":{"end":[26,35],"start":[26,24]}},"type":"Literal","value":{"literalType":"ArrayLiteral","value":[{"annotation":{"meta":null,"sourceSpan":{"end":[26,27],"start":[26,26]}},"type":"Literal","value":{"literalType":"IntLiteral","value":7}},{"annotation":{"meta":null,"sourceSpan":{"end":[26,30],"start":[26,29]}},"type":"Literal","value":{"literalType":"IntLiteral","value":8}},{"annotation":{"meta":null,"sourceSpan":{"end":[26,33],"start":[26,32]}},"type":"Literal","value":{"literalType":"IntLiteral","value":9}}]}},"type":"App"},"type":"App"},"type":"Abs"},"type":"App"},"type":"Abs"},"type":"App"},"type":"Abs"},"type":"App"},"identifier":"main"}],"exports":["firstTwo","lastOfThree","main"],"foreign":[],"imports":[{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Control","Bind"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Data","Ring"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Data","Semiring"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Data","Show"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Effect"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Effect","Console"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Golden","ArrayPatternMatch","Test"]},{"annotation":{"meta":null,"sourceSpan":{"end":[3,15],"start":[3,1]}},"moduleName":["Prelude"]},{"annotation":{"meta":null,"sourceSpan":{"end":[26,36],"start":[1,1]}},"moduleName":["Prim"]}],"moduleName":["Golden","ArrayPatternMatch","Test"],"modulePath":"golden/Golden/ArrayPatternMatch/Test.purs","reExports":{},"sourceSpan":{"end":[26,36],"start":[1,1]}}
1 change: 1 addition & 0 deletions test/ps/output/Golden.ArrayPatternMatch.Test/eval/.gitignore
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
actual.txt
4 changes: 4 additions & 0 deletions test/ps/output/Golden.ArrayPatternMatch.Test/eval/golden.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
30
-1
-1
9
Loading
Loading