Primitive Types

The following primitive types exist in WDL:

• A Boolean represents a value of true or false.
• An Int represents a signed 64-bit integer (in the range [-2^63, 2^63)).
• A Float represents a finite 64-bit IEEE-754 floating point number.
• A String represents a unicode character string following the format described below.
• A File represents a file (or file-like object).
• A Directory represents a (possibly nested) directory of files.

Example: primitive_literals.wdl

version 1.3

task write_file_task {
  command <<<
  mkdir -p testdir
  printf "hello" > testdir/hello.txt
  >>>

  output {
    File x = "testdir/hello.txt"
    Directory d = "testdir"
  }
}

workflow primitive_literals {
  call write_file_task

  output {
    Boolean b = true
    Int i = 0
    Float f = 27.3
    String s = "hello, world"
    File x = write_file_task.x
    Directory d = write_file_task.d
  }
}

{}

{
  "primitive_literals.b": true,
  "primitive_literals.i": 0,
  "primitive_literals.f": 27.3,
  "primitive_literals.s": "hello, world",
  "primitive_literals.x": "hello.txt",
  "primitive_literals.d": "testdir"
}

All primitive WDL types serialize naturally to JSON values:

JSON has a single numeric type - it does not differentiate between integral and floating point values. A JSON number is always deserialized to a WDL Float, which may then be coerced to an Int if necessary.

JSON does not have a specific type for filesystem paths, but a WDL String may be coerced to a File if necessary.