Spec Change Tracking

[jdidion]

This thread will track proposed changes to the WDL specification, grouped first by status and then by topic (as there are sometimes multiple proposals on the same topic). This is meant to be a living thread that should be updated whenever a proposal is added, withdrawn, or changes status.

Active

Approved

Implemented, ready to merge

• Clarify sub() function regular expressions
  • POSIX ERE
  • Use Google RE2 library if possible
• Struct literals
  • Specifies new literal syntax for defining structs - replaces object literal syntax
• min, max functions
  • Adds min() and max() to the standard library
• runtime changes and new hints section
  • The runtime section specifies which keys are allowed - arbitrary keys are no longer allowed
  • Adds a new hints section that allows arbitrary keys with meta-type values (i.e. no expressions)

Awaiting implementations

• Revert "Clarify type conversions and meanings"
  • I don't understand what this one is about - can someone please add context?
• Unsatisfied task inputs
  • Specify how inputs are passed from the top-level workflow to subworkflow/task calls
  • Specifies a allowNestedInputs attribute that should be recognized in the workflow meta section, indicating the engine should allow nested inputs to be specified via the input JSON
  • Satisfies/obsoletes: Allow passthrough of inputs from the inputs.json to a subworkflow #262
  • May obsolete: Mapping inputs for sub-workflow calls #217
• File outputs
  • Specify how file and optional outputs are represented in the task/workflow output
  • Satisfies/obsoletes:
    • Optional Outputs #20
    • Does WDL support optional outputs? #394

Voting in progress

• Formal specification of namespaces and scoping
  • May satisfy/obsolete Simplify call syntax: make 'input:' keyword optional #198

Proposed with pull-request

• Pass-through syntax for call inputs
  • Proposes a simplified syntax for passing workflow inputs to calls
• Multi-line strings
  • Proposes a Python/Scala-like syntax for multi-line strings
  • By default, multi-line strings would not preserve trailing/leading whitespace, but alternate forms are proposed for cases where it is desired to preserve whitespace

Under discussion

Array slicing

• either function or syntax change
• split function

Reading structured data

• Read TSV with headers
• Reading structured data from TSV/JSON
• Reading array of objects
• read_* functions return empty values for missing optional files

Type coercion

• Automatic coercion to String for concatenation within placeholders
• File/String concatenation
• implicit coercions and explicit casting syntax
  • Additional context: Automatic Coercions Considered Harmful #373
• type inference

Evaluation of non-bash scripts

• User-defined functions
• eval function

Other syntax changes

• Scatter over Map
• allow integer indexing of Pair
• enumerations
• parameter_meta for structs
• multi-line strings
• else clause for conditionals
• file bundles/secondary files
• exponentiation operator
• arbitrary length tuples and tuple unpacking
• struct namespacing
• type aliases
• explicit namespaces for WDL files
• WDL file versioning
• Inline Docker files
• Interpreter runtime attribute
• templates
• resources block

Other additions/changes to the standard library

• Search for files using a regular expression
• sum
• startsWith/endsWith/contains
• test whether an Array contains a value
• test whether a Map contains a key
• get value for Map key
• total input size

Other feature requests that may be solved by either syntax or library changes

• apply function to array

Inactive

Merged

Abandoned or rejected