Skip to content

predicate-reference.md

Latest commit

 

History

History
103 lines (65 loc) · 2.02 KB

predicate-reference.md

File metadata and controls

103 lines (65 loc) · 2.02 KB
Raw

Predicate reference

Predicates are used by both when and requires.

Semantics

  • each predicate list is an AND
  • ! negates a single predicate atom
  • predicates are parsed by conch
  • during check, init, and explain, predicates remain descriptive and are not evaluated against the host
  • during build, shell, command, file, dir, os, and hostname are folded on the current machine, while interactive, login, and all env:* predicates remain runtime checks
  • any predicates that survive are evaluated by the generated shell code when sourced

Supported atoms

interactive

Session is interactive.

login

Session is a login shell.

shell:<name>

Target shell matches the given shell name. Examples:

  • shell:fish
  • shell:bash

command:<name>

A command exists in PATH. Example:

  • command:nvim

env:<name>

An environment variable exists and is non-empty. Example:

  • env:EDITOR

env:<name>=<value>

An environment variable equals a literal value. Example:

  • env:VISUAL=nvim

file:<path>

A path exists (file or directory). Example:

  • file:~/.config/nvim/init.lua
  • file:~/.config/nvim

dir:<path>

A path exists and is a directory. Example:

  • dir:~/.config/nvim

os:<name>

Operating system matches a name. Example:

  • os:linux

hostname:<name>

Hostname matches a name. Example:

  • hostname:workstation

Negation examples

  • !interactive
  • !command:nvim
  • !env:EDITOR

Examples

when = ["interactive", "shell:fish"]
requires = ["command:nvim"]
when = ["!env:EDITOR"]
requires = ["file:~/.local/bin/nvim"]
requires = ["dir:~/.local/bin"]

v1 notes

  • conch validates predicate syntax but does not evaluate predicates during check/init/explain
  • build folds only shell, command, file, dir, os, and hostname, and does so on the current machine
  • providers compile any remaining predicates into shell-native checks
  • conflict detection does not attempt predicate satisfiability or mutual-exclusion reasoning