Table 1.
Summary of language-level differences among Swift/T, Nextflow, CWL and WDL.
| Aspect | Swift/T | Nextflow | CWL | WDL |
|---|---|---|---|---|
| Parent language | C, tcl | Ruby and Groovy | N/A | N/A |
| Compilation | Compiled | Interpreted | Compiled | Compiled |
| GUIs | – | NextflowWorkbench27, DolphinNext28 | Rabix composer | Pipeline Builder29 |
| DSL features | Complete, extensible in tcl | complete, extensible in Groovy and Java | Limited standard library, extensible via javascript | Limited standard library |
| Variables | Typed, unique within scope | Qualified, unique within scope | Typed, unique identifiers | Typed, fully qualified names |
| Loops | Sequential for and parallel foreach | Parallel queue channels | Parallel scatter via ScatterFeatureRequirement | Parallel scatter |
| Conditionals | If-else and no-fall through switch statements | Via when declaration within a process | When and pickValue fields proposed in CWLv1.2 | If blocks producing optional output types |
| Enforcing good practices | – | nf-core (https://nf-co.re/) | CWL guide (https://www.commonwl.org/user_guide/rec-practices/) | – |