add devcontainer

.devcontainer/Dockerfile

@@ -0,0 +1,57 @@
+FROM alpine:latest
+
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+# Install required packages (Alpine equivalents)
+RUN apk add --no-cache \
+    curl \
+    ca-certificates \
+    git \
+    build-base \
+    gmp-dev \
+    zlib-dev \
+    sudo \
+    bash \
+    libc6-compat \
+    ncurses-dev \
+    xz
+
+# Create user with sudo access
+RUN addgroup -g $USER_GID $USERNAME && \
+    adduser -D -s /bin/bash -u $USER_UID -G $USERNAME $USERNAME && \
+    mkdir -p /etc/sudoers.d && \
+    echo "$USERNAME ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/$USERNAME && \
+    chmod 0440 /etc/sudoers.d/$USERNAME
+
+USER $USERNAME
+WORKDIR /home/$USERNAME
+
+RUN mkdir -p /home/$USERNAME/.ghcup/bin
+
+# Install GHCup
+RUN curl -sSL https://downloads.haskell.org/~ghcup/x86_64-linux-ghcup -o /home/$USERNAME/.ghcup/bin/ghcup && \
+    chmod +x /home/$USERNAME/.ghcup/bin/ghcup
+
+ENV PATH="/home/$USERNAME/.ghcup/bin:/home/$USERNAME/.cabal/bin:${PATH}"
+
+# Install Haskell toolchain
+RUN ghcup install ghc 9.12.2 && \
+    ghcup set ghc 9.12.2 && \
+    ghcup install hls 2.10.0.0 && \
+    ghcup set hls 2.10.0.0 && \
+    ghcup install cabal 3.14.2.0 && \
+    ghcup set cabal 3.14.2.0 && \
+    ln -sf /home/$USERNAME/.ghcup/bin/haskell-language-server-wrapper /home/$USERNAME/.ghcup/bin/hls
+
+# Set up the PATH in bashrc
+RUN echo 'export PATH="/home/'$USERNAME'/.ghcup/bin:/home/'$USERNAME'/.cabal/bin:$PATH"' >> /home/$USERNAME/.bashrc
+
+# Verify installations
+RUN ghc --version && cabal --version && hls --version
+
+# Update cabal package list
+RUN cabal update
+
+ENTRYPOINT ["/bin/bash"]

.devcontainer/devcontainer.json

@@ -0,0 +1,13 @@
+{
+  "name": "Haskell DevContainer (GHCup)",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+  "settings": {
+    "haskell.manageHLS": "GHCup"
+  },
+  "extensions": [
+    "haskell.haskell"
+  ],
+  "remoteUser": "vscode"
+}

CLAUDE.md

@@ -6,7 +6,7 @@ It is structured as follows:
 
 - bend.cabal: the cabal file. Bend doesn't use stack.
   - Build this project with `cabal build`.
-  - Run with `bend file.bend`.
+  - Run with `cabal run bend file.bend`.
 
 - src/Core/Type.hs: most important file, always read. Includes every type used in
   this repo, including the Term type for Bend's core language.