Big tracking issue for implementing standard functions

[sagebind]

For Riptide to be useful at all, a minimal list of builtin functions and constructs must be provided in order to be able to program properly. Below is a list of functions that should be implemented before an alpha release:

• =: Test equivalence.
• |: Create a pipeline.
• and: Logical and.
• apply: Function call argument unpacking.
• begin: Execute expressions in sequence.
• builtin: Explicitly call a builtin.
• capture: Capture stdout and return it.
• cd: Change directory.
• command: Explicitly call a command.
• cond: Multiple conditional branching.
• def: Define a global function or variable (binding).
• let: Define a local, lexically scoped binding.
• env: Get, set, or list environment variables.
• exec: Replace current process.
• exit: Exit program.
• foreach: Iterate over a list.
• help: Some sort of help system.
• if: Conditional branching.
• list: Create a list.
• not: Negate a boolean.
• nth: Return nth item in list.
• or: Logical or.
• print: Write to output.
• pwd: Print current directory.
• read: Read from input.
• source: Evaluate a script file.

(update this list as needed)