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Yglu ᕄ !?

Yglu is YAML augmented with an advanced expression language. Unlike usual text templating, Yglu relies on the YAML structure and leverages its tag system combined with the YAQL query language.

This association enables templating and functional processing a bit like if YAML nodes were spreadsheet cells.

Yglu input documents are pure and valid YAML using tags for computed nodes.

a: 1
b: !? .a + 1
!if .b = 2:
  c: 3  

a: 1
b: 2 
c: 3
 

names: !-
  - 'nginx:1.16'
  - 'node:13.6'
  - 'couchbase:9.3'
image: !()
  !? $.split(':')[0]: 
    version: !? $.split(':')[1]
images: !? 
  $_.names
    .select(($_.image)($))
    .aggregate($1.mergeWith($2), {})

images:
  nginx: 
    version: '1.16'
  node: 
    version: '13.6'
  couchbase: 
    version: '9.3'
     
     
     
       

In the example above, the names sequence is hidden, image is a function (like a template block) and images is an expression which iterates through all names, applies the image function to each one and aggregates the individual results by merging them together as a mapping.

As such an operation is often needed, Yglu provides a !for tag for merging a sequence iterated over a function:

names: !-
  - 'nginx:1.16'
  - 'node:13.6'
  - 'couchbase:9.3'
images: 
  !for .names: !()
    !? $.split(':')[0]:
      version: !? $.split(':')[1]

images:
  nginx: 
    version: '1.16'
  node: 
    version: '13.6'
  couchbase: 
    version: '9.3'
     

See the test samples for more examples.

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Install

pip3 install yglu

Run

Usage: yglu [options] [<filename>]

Options:
  -v - -version          Print version and exit.
  -h - -help             Print help and exit.

Tags

Tags specify an alteration of the document structure.

Expressions

Expressions are written in YAQL.

They are evaluated in a context with the following variables defined:

Built-in Functions

In addition to the standard YAQL library, Yglu defines the following functions: