diff options
Diffstat (limited to 'guix/utils.scm')
| -rw-r--r-- | guix/utils.scm | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/guix/utils.scm b/guix/utils.scm index 7ebc026702..fa5abadc7a 100644 --- a/guix/utils.scm +++ b/guix/utils.scm @@ -49,6 +49,8 @@ define-record-type* compile-time-value memoize + default-keyword-arguments + substitute-keyword-arguments location location? @@ -546,6 +548,37 @@ FIELD/DEFAULT-VALUE tuples." (hash-set! cache args results) (apply values results))))))) +(define (default-keyword-arguments args defaults) + "Return ARGS augmented with any keyword/value from DEFAULTS for +keywords not already present in ARGS." + (let loop ((defaults defaults) + (args args)) + (match defaults + ((kw value rest ...) + (loop rest + (if (assoc-ref kw args) + args + (cons* kw value args)))) + (() + args)))) + +(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) + (before '())) + (match args + ((kw var rest (... ...)) + (loop rest (cons* exp kw before))) + ... + ((x rest (... ...)) + (loop rest (cons x before))) + (() + (reverse before))))))) + (define (gnu-triplet->nix-system triplet) "Return the Nix system type corresponding to TRIPLET, a GNU triplet as returned by `config.guess'." |