Small snippets of Guile Scheme
There’s a lot of implicit knowledge among Guile developers. Here I gather some useful snippets I found along the way.
More useful stuff to get things done in Guile is available in guile-basics and py2guile.
Use Guile-yaml to search for the first match in a yaml file
This uses guile-libyaml to parse the yaml file and (ice-9 match) to recursively search within the file.
The example file is demo1.yml from the guile-yaml repo:
---
doe: "a deer, a female deer"
ray: "a drop of golden sun"
pi: 3.14159
xmas: true
french-hens: 3
calling-birds:
- huey
- dewey
- louie
- fred
xmas-fifth-day:
calling-birds: four
french-hens: 3
golden-rings: 5
partridges:
count: 1
location: "a pear tree"
turtle-doves: two
I’m searching for the first match to "partridges":
(import (yaml) (ice-9 match)) (define demo (read-yaml-file "demo1.yml")) (let match-demo ((demo demo)) (match demo ((("partridges" . b) c ...) b) (else (if (pair? demo) (or (match-demo (cdr demo)) (match-demo (car demo))) #f)))) ;; => (("count" . "1") ("location" . "a pear tree"))
To use this snippet, start guile as guile -L . in the guile-libyaml repo.