hscript

#!/usr/bin/env bash
# Usage: hscript input.hs
# Note: this file was partially generated with an LLM.

mkdir -p /tmp/hscript

awk '
function reset_block() {
  block_len = 0;
}

function push_line(line) {
  block[block_len++] = line;
}

# Heuristics for "IO / Template Haskell-ish" lines
function is_special(line) {
  # Contains:
  #   - <-
  #   - $( ... )
  #   - declareColumns
  #   - D.derive ...
  return (line ~ /<-/ ||
          line ~ /[$][(]/ ||
          line ~ /declareColumns/ ||
          line ~ /D[.]derive/);
}

function flush_block() {
  if (block_len == 0) return;

  lang_or_import = 1;   # all LANGUAGE/imports?
  all_special    = 1;   # every line is IO/TH-ish?
  any_special    = 0;   # at least one IO/TH-ish line?

  for (i = 0; i < block_len; i++) {
    line = block[i];

    if (line !~ /^{-# LANGUAGE/ && line !~ /^import[[:space:]]+/) {
      lang_or_import = 0;
    }

    if (is_special(line)) {
      any_special = 1;
    } else {
      all_special = 0;
    }
  }

  if (all_special && block_len > 0) {
    # All IO/TH-ish: each gets its own :{ ... :}
    for (i = 0; i < block_len; i++) {
      print ":{";
      print block[i];
      print ":}";
    }
  } else if (lang_or_import || block_len > 1 || any_special) {
    # Multi-line chunk, or imports/pragmas, or a single special line
    print ":{";
    for (i = 0; i < block_len; i++) {
      print block[i];
    }
    print ":}";
  } else {
    # Single, non-special line (e.g. `default (Int, T.Text)`)
    for (i = 0; i < block_len; i++) {
      print block[i];
    }
  }

  reset_block();
}

BEGIN {
  reset_block();
}

# GHCi-style commands (e.g. :set, :load) — pass through
/^[[:space:]]*:/ {
  flush_block();
  print;
  next;
}

# Blank line: end current chunk, keep blank
NF == 0 {
  flush_block();
  print "";
  next;
}

# Any other line is part of the current Haskell chunk
{
  push_line($0);
}

END {
  flush_block();
}
' "$@" > /tmp/hscript/script.ghci

ghc -e ':script /tmp/hscript/script.ghci'