diff options
Diffstat (limited to 'guix/utils.scm')
| -rw-r--r-- | guix/utils.scm | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/guix/utils.scm b/guix/utils.scm index c68094cf49..decadf64a6 100644 --- a/guix/utils.scm +++ b/guix/utils.scm @@ -369,19 +369,30 @@ keywords not already present in ARGS." (match defaults ((kw value rest ...) (loop rest - (if (assoc-ref kw args) + (if (memq kw args) args (cons* kw value args)))) (() args)))) +(define-syntax collect-default-args + (syntax-rules () + ((_) + '()) + ((_ (_ _) rest ...) + (collect-default-args rest ...)) + ((_ (kw _ dflt) rest ...) + (cons* kw dflt (collect-default-args rest ...))))) + (define-syntax substitute-keyword-arguments (syntax-rules () "Return a new list of arguments where the value for keyword arg KW is -replaced by EXP. EXP is evaluated in a context where VAR is boud to the -previous value of the keyword argument." - ((_ original-args ((kw var) exp) ...) - (let loop ((args original-args) +replaced by EXP. EXP is evaluated in a context where VAR is bound to the +previous value of the keyword argument, or DFLT if given." + ((_ original-args ((kw var dflt ...) exp) ...) + (let loop ((args (default-keyword-arguments + original-args + (collect-default-args (kw var dflt ...) ...))) (before '())) (match args ((kw var rest (... ...)) |