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| author | Arun Isaac | 2023-11-17 23:24:00 +0000 |
|---|---|---|
| committer | Arun Isaac | 2023-11-17 23:24:00 +0000 |
| commit | 6842628dc5345b47ca7ce99ea5eba119cd5741e6 (patch) | |
| tree | 4d9d9a4d60c2e04c7ea12b40a0dcc7c29fd00b69 /ccwl | |
| parent | bac6c575e7c03a1946ea46379a5bc98f009408fd (diff) | |
| download | ccwl-6842628dc5345b47ca7ce99ea5eba119cd5741e6.tar.gz ccwl-6842628dc5345b47ca7ce99ea5eba119cd5741e6.tar.lz ccwl-6842628dc5345b47ca7ce99ea5eba119cd5741e6.zip | |
utils: Define pairify behaviour on odd number of elements.
* ccwl/utils.scm (pairify): Ignore extra elements when list has an odd
number of elements.
* tests/utils.scm ("pairify must ignore extra elements when list has
an odd number of elements"): New test.
Diffstat (limited to 'ccwl')
| -rw-r--r-- | ccwl/utils.scm | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/ccwl/utils.scm b/ccwl/utils.scm index 508e884..d9d1ee3 100644 --- a/ccwl/utils.scm +++ b/ccwl/utils.scm @@ -1,5 +1,5 @@ ;;; ccwl --- Concise Common Workflow Language -;;; Copyright © 2021, 2022 Arun Isaac <arunisaac@systemreboot.net> +;;; Copyright © 2021, 2022, 2023 Arun Isaac <arunisaac@systemreboot.net> ;;; ;;; This file is part of ccwl. ;;; @@ -48,12 +48,17 @@ (display (make-string (* 2 level) #\space) port)) (define (pairify lst) - "Return a list of pairs of successive elements of LST. For example, + "Return a list of pairs of successive elements of LST. Ignore extra +elements when LST has an odd number of elements. For example, (pairify (list 1 2 3 4 5 6)) +=> ((1 . 2) (3 . 4) (5 . 6)) + +(pairify (list 1 2 3 4 5 6 7)) => ((1 . 2) (3 . 4) (5 . 6))" (match lst (() '()) + ((single-element) '()) ((first second tail ...) (cons (cons first second) (pairify tail))))) |