Feature Comparison

You already know Python. Why learn another DSL?

jq / yq — powerful but you need to learn a custom query language:

# jq: filter users older than 30
jq '[.[] | select(.age > 30)]' users.json

# fimod: same idea, with Python syntax
fimod s -i users.json -e '[u for u in data if u["age"] > 30]'

# jq: project + sort + deduplicate
jq '[.[] | {id, name}] | sort_by(.name) | unique_by(.id)' data.json

# fimod: chain expressions, each feeds the next
fimod s -i data.json -e '[{"id": u["id"], "name": u["name"]} for u in data]' \
  -e 'it_sort_by(data, "name")' -m @dedup_by --arg field=id

# yq: convert YAML → JSON
yq -o json config.yaml

# fimod: any format → any format
fimod s -i config.yaml -e 'data' -o config.toml

yq also supports CSV/TSV encode, decode, and round-trips, plus TOML input. Fimod's distinction is one Python-shaped transform and mold workflow across its supported formats, not the absence of those formats in yq.

Python one-liner — works but painful boilerplate:

python3 -c "
import json, sys
data = json.load(sys.stdin)
print(json.dumps([u for u in data if u['active']]))
" < users.json

# fimod: same logic, zero boilerplate, no Python install
fimod s -i users.json -e '[u for u in data if u["active"]]'

Matrix

	jq	yq	Python script	fimod
Language	jq DSL	jq-like DSL	Python	🟢 Python
JSON	✅	✅	manual I/O	🟢 built-in
YAML	❌	✅	manual I/O	🟢 built-in
TOML	❌	✅ (read-only)	manual I/O	🟢 built-in
CSV	❌	✅ (limited)	manual I/O	🟢 built-in
NDJSON	✅ (--slurp)	❌	manual I/O	🟢 built-in (--slurp)
Cross-format	❌	multiple formats (limits vary)	manual	🟢 any → any
Dependencies	jq binary	yq binary	Python + pip	🟢 single binary
Binary size	~2 MB	~10 MB	~30-100 MB (standalone)	🟢 ~3.3 MB standard (UPX-compressed; `slim` is smaller)
Speed-tuned build	n/a	n/a	custom packaging	🟢 `fimod-fast` (~15-25% faster on CPU-heavy smoke tests; larger, uncompressed)
Regex	built-in	RE2	`import re`	🟢 `import re` (Monty)
Deep access	`.a.b.c`	`.a.b.c`	manual	🟢 `dp_get(data, "a.b.c")`
Group/sort/unique	`group_by`	`group_by`	manual	🟢 `it_group_by`, `it_sort_by`, `@dedup_by`
Hashing	❌	❌	`import hashlib`	🟢 `hs_sha256`, `hs_md5`, `hs_sha1`
In-place edit	sponge hack	`-i`	manual	🟢 `--in-place`
Batch files	loop	loop	loop	🟢 `fimod s -i *.json -m t.py -o out/`
Chaining	`\|` (inside jq)	`\|` (inside yq)	manual	🟢 `-e expr1 -e expr2`
Exit codes	✅ `-e`	✅ `-e`	`sys.exit()`	🟢 `--check` + `set_exit()`
Reusable scripts	❌	❌	yes	🟢 mold scripts + registry
Remote scripts	❌	❌	❌	🟢 `-m https://...`
HTTP input	❌	❌	`requests` + boilerplate	🟢 `-i https://...` (replaces curl)
Test runner	❌	❌	pytest	🟢 `fimod mold test mold.py tests/`