{"atom":"regression/seq-generator-shapes","family":"regression","slug":"seq-generator-shapes","header":{"atom":"regression/seq-generator-shapes","kind":"whole-program — a minimal repro, not yet reduced to an atom","source":"curated"},"axes":null,"cols":null,"engines":["rakudo-2026.07","rakupp-3.14.0"],"kinds":["ref","pp"],"defFrom":"rakupp:t/regression/seq-generator-shapes.raku","counts":{"a":1,"f":0,"d":0,"c":0,"r":0,"n":0},"files":["atoms/regression/seq-generator-shapes.grid"],"records":[["0001","","# BROKE (during the sequence leg, caught by gate sq1): allowing an empty\n# seed for closure-only sequences (`{ 3+2 } ... *`) let an EMPTY list\n# reach the bounded generator loop, whose back() on empty was UNDEFINED\n# BEHAVIOR — context-dependent silent death (S03-sequence/basic.t ended\n# mid-file only in file context; limit-arity-2-or-more.t hung).\n# FIXED: same leg — lastV guards the empty case; a runaway cap bounds\n# generator sequences whose literal endpoint never matches.\ndie 'alternating endpoint-miss broken'\n    unless (1, { -$_ } ... 3).[^5].join(',') eq '1,-1,1,-1,1';\ndie 'closure-only seed broken'\n    unless ({ 3+2 } ... *).[^3].join(',') eq '5,5,5';\ndie 'gen with reachable endpoint broken'\n    unless (1, { $_ + 1 } ... 5).join(',') eq '1,2,3,4,5';\ndie 'empty-seed with Code endpoint broken (the UB shape)'\n    unless do { my $i = -5; ({ ++$i; $i**3-9*$i } ... { ($^a-$^b) > ($^b-$^c) }).elems > 0 };\ndie 'plain sequences broken'\n    unless (1, 2 ... 10).join(',') eq '1,2,3,4,5,6,7,8,9,10';\nsay 'PASS';","output PASS","a",["PASS","PASS"],0,[["budget","20s"]]]]}