From e99298d8719c71ff23921fdb9a79197880ac5bfc Mon Sep 17 00:00:00 2001 From: Tom Smeding Date: Thu, 21 Nov 2019 23:23:38 +0100 Subject: Rotate arguments to substr and allow negative length --- VM.hs | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'VM.hs') diff --git a/VM.hs b/VM.hs index 64674fb..ea94597 100644 --- a/VM.hs +++ b/VM.hs @@ -152,8 +152,9 @@ vmRunBuiltin state "sys-stdin" [] = return (RVNum (-1), state) vmRunBuiltin state "sys-stdout" [] = return (RVNum (-2), state) vmRunBuiltin state "sys-stderr" [] = return (RVNum (-3), state) vmRunBuiltin state "length" [RVString str] = return (RVNum (length str), state) -vmRunBuiltin state "substr" [RVString str, RVNum idx, RVNum len] = - return (RVString (take len (drop idx str)), state) +vmRunBuiltin state "substr" [RVNum idx, RVNum len, RVString str] = + let s = (if len >= 0 then take len else id) (drop idx str) + in return (RVString s, state) vmRunBuiltin state "ord" [RVString str] = return (RVNum (case str of { "" -> 0; c:_ -> ord c }), state) vmRunBuiltin state "chr" [RVNum num] = return (RVString [chr num], state) vmRunBuiltin state "concat" values -- cgit v1.2.3-54-g00ecf