# Godwit

A compiler for a functional pattern language (based on simply-typed lambda calculus with Tidal-inspired maxi-notation syntax) to C via cartesian closed categories.

# 1 Bird

https://www.rspb.org.uk/birds-and-wildlife/black-tailed-godwit

# 2 Uzulang

Godwit is an Uzulang. An Uzulang is a member of a family of languages in the style of TidalCycles. Other Uzulangs are available.

# 3 Code

git clone https://code.mathr.co.uk/godwit.git

Very early days so far, don’t expect much.

# 4 Bootstrap

This is a script I use to install/update Godwit using MicroHs (a Haskell compiler that is much smaller than GHC, and more up to date than Hugs). It fetches the latest MicroHs, dependencies of Godwit, and Godwit itself, and rebuilds it all if the fetched version is newer than the currently installed MicroHs.

Currently needs alex and happy parser generation tools.

The script has some bugs re git stash (might pop an old one…).

Download: bootstrap.sh.

#!/bin/sh
set -ev
FORCE="${1}"
OLD="$(mhs --numeric-version || echo none)"
( git clone https://github.com/augustss/MicroHs.git || (cd MicroHs && git stash && git pull && (git stash pop || true)) )
( git clone https://github.com/augustss/mtl.git || (cd mtl && git stash && git pull && (git stash pop || true)) )
( git clone https://github.com/haskell/containers.git || (cd containers && git stash && git pull && (git stash pop || true)) )
( git clone https://code.mathr.co.uk/godwit.git || (cd godwit && git stash && git pull && (git stash pop || true)) )
NEW="$(grep '^version:' MicroHs/MicroHs.cabal | sed -e 's/^version: *//')"
if [ "x$OLD" != "x$NEW" -o "x$FORCE" = "x--force" ]
then
  rm -rf "${HOME}/.mcabal/mhs-$OLD"
  ( cd MicroHs && make clean && make install )
  PATH="${HOME}/.mcabal/bin:${PATH}"
  ( mcabal install transformers )
  ( cd mtl && mcabal install )
  ( cd containers/containers && mcabal install )
  ( cd godwit && make HC=mhs clean && make HC=mhs -j "$(nproc)" )
fi

# 5 Download

If you don’t have alex or happy, and don’t plan on editing the parser definition, you can download a snapshot which includes pre-generated Parser.hs and Lexer.hs:

You can use these files with post v0 main branch, they haven’t changed.

Future versions of godwit will abandon alex and happy (which work with GHC only) in favour of parsec, which is much more portable.

You still need the other Haskell dependencies (transformers, mtl, containers) (see bootstrap script above for installation with MicroHs).

# 6 Usage

Example pattern (needs to be all on one line):

cps (pure $ 0.18 `fmul` 1.8 `fmul` 1.8) `u`
_early (qi 18) (sound [bd*18,[~ sn]*9,[~ ht/3 mt]*6]) `u`
shape [0.8] `u`
gain [0.18] `u`
let seq = [18] `isubR` run 18
in (seq `imulL` _slow (qi 18) (seq `imulL` _slow (qi 18) seq)) `bind`
\x -> stack (map
  (\y -> let z = imod x y in ifte (igt z 0) (pure z) silence)
  (empty : 2 : 3 : 6 : 9 : 18)) `bind`
\x -> n (pure (ffromi x)) `u`
speed (flip fdiv 18.0 . ffromi . iadd (imul 18 2)
  . flip imod 18 . iadd (imul 13 x) . imul 5 $$ _slow (qi 18) seq)

Based on my Strudel looptober 2024 #18.