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Host functions

FScript provides the language and standard library documented in the FScript manual. Terrabuild controls which host functions an extension may call.

Terrabuild exposes the default FScript host registry except for concurrency and interactive-input functions that do not fit deterministic build-graph evaluation:

  • Task.spawn
  • Task.await
  • Console.readLine

Functions available to extensions​

Filesystem​

  • Fs.readText
  • Fs.exists
  • Fs.kind
  • Fs.createDirectory
  • Fs.writeText
  • Fs.combinePath
  • Fs.parentDirectory
  • Fs.extension
  • Fs.fileNameWithoutExtension
  • Fs.glob
  • Fs.enumerateFiles

Filesystem access is confined to the workspace root. Paths matching workspace.deny are unavailable; the default deny list is [ ".git" ].

Data and utilities​

  • Regex.matchGroups
  • Hash.md5
  • Guid.new
  • Json.deserialize
  • Json.serialize
  • Xml.queryValues

Output​

  • Console.writeLine

Return ShellOperation values to request commands. Host functions run while Terrabuild evaluates the extension. Shell operations run later under the graph's scheduling, container, caching, and failure rules.

For the language's built-in modules and functions, use the FScript standard-library reference.