snc2fst

Installation

conda install -c conda-forge mazadegan::snc2fst

Rule DSL

Rules are written in config.toml under [[rules]]. Inr describes the target window, Trm describes the trigger/terminator window, Dir is L or R, and Out is the replacement expression.

[[rules]]
Id = "R1"
Dir = "L"
Inr = [["-Syllabic"], ["+Strident"]]
Trm = [[]]
Out = "(INR[1] &E INR[2])"

Inr and Trm are sequences of natural classes. Each inner list describes one segment position:

• ["+F", "-G"] matches a segment that is +F and -G.
• [] matches any segment.
• "*F" matches either +F or -F, but not a segment where F is unspecified. It can be combined with ordinary feature requirements, as in ["*F", "+G"].

A natural-class sequence matches a word position by position. For example, Inr = [["+F"], ["-G"]] matches exactly two adjacent segments: the first must be +F, and the second must be -G. The same idea is used inside expressions with bracket syntax: [{+F} {-G}] is a two-position natural-class sequence, and (in? TRM [{+F} {-G}]) is true only when TRM has that shape. Use Trm = [] for no trigger window; use Trm = [[]] for a one-segment trigger that can be any segment.

Out and optional Cnd expressions are written over the currently matched windows:

• INR and TRM refer to the whole target and trigger windows.
• INR[1] selects one segment. Indices are 1-based.
• INR[1:3] selects an inclusive slice, here positions 1 through 3.
• Parentheses concatenate expressions, so (INR[2] INR[1]) metathesizes a two-segment target and (INR[1:4] INR[2:4]) duplicates a slice.
• &A inserts the named segment A from the alphabet.
• {+F -G} creates an underspecified segment with those feature values.

Supported operations are:

• (unify INR[1] {+F}) unifies a segment with the given feature values.
• (subtract INR[1] {-G}) removes matching feature values from a segment.
• (proj TRM[1] (Voice Back)) keeps only the named features from a segment.
• (in? TRM [{+F} {-G}]) tests whether a word belongs to a natural-class sequence.
• (if CONDITION THEN ELSE) chooses between two expressions.

Whitespace is ignored, and ; starts a line comment inside Out or Cnd. Feature bundles and natural-class sequences are space-separated, not comma-separated: write {+F -G} and [{+F} {-G}].

Developer Notes

Setup

pip install -e .

Releasing a new version

1. Bump the version in pyproject.toml and conda-recipe/meta.yaml.

2. Build the conda package:

conda-build conda-recipe -c mazadegan -c conda-forge -c defaults

3. Test the local build before uploading:

conda install ~/miniforge3/envs/snc2fst/conda-bld/noarch/snc2fst-<version>-*.conda

4. Upload to anaconda channel:

anaconda login
anaconda upload ~/miniforge3/envs/snc2fst/conda-bld/noarch/snc2fst-<version>-*.conda

License

Apache 2.0. See LICENSE.