Run in Eval mode

Use eval command to evaluate code snippets from CLI:

$ cr eval 'echo |demo'
1
took 0.07ms: nil

$ cr eval 'echo "|spaced string demo"'
spaced string demo
took 0.074ms: nil

Multi-line Code

You can run multiple expressions:

cr eval '
-> (range 10)
  map $ fn (x)
    * x x
'
# Output: calcit version: 0.5.25
# took 0.199ms: ([] 0 1 4 9 16 25 36 49 64 81)

Working with Context Files

Eval can access definitions from a loaded program:

# Load from specific file and eval with its context
cr demos/compact.cirru eval 'range 3'
# Output: ([] 0 1 2)

# Use let bindings
cr demos/compact.cirru eval 'let ((x 1)) (+ x 2)'
# Output: 3

You can load external modules with repeatable --dep options:

cr demos/compact.cirru eval --dep ~/.config/calcit/modules/respo.calcit/ -- 'ns app.demo $ :require respo.util.detect :refer $ element?\n\nelement? nil'

If the first expression in a snippet is ns, its :require rules are merged into runtime ns app.main, so imported symbols can be used in the same snippet.

Type Checking in Eval

Type annotations and static checks work in eval mode:

# Type mismatch will cause error
cr demos/compact.cirru eval 'let ((x 1)) (assert-type x :string) x'
# Error: Type mismatch...

# Correct type passes
cr demos/compact.cirru eval 'let ((x 1)) (assert-type x :number) x'
# Output: 1

Common Patterns

Quick Calculations

cr eval '+ 1 2 3 4'
# Output: 10

cr eval 'apply * $ range 1 6'
# Output: 120  ; factorial of 5

Testing Expressions

cr eval '&list:nth ([] :a :b :c) 1'
# Output: :b

cr eval '&map:get ({} (:x 1) (:y 2)) :x'
# Output: 1

Exploring Functions

# Check function signature
cr eval 'type-of range'
# Output: :fn

# Test with sample data
cr eval '-> (range 5) (map inc) (filter (fn (x) (> x 2)))'
# Output: ([] 3 4 5)

Important Notes

Syntax Considerations

No extra brackets: Cirru syntax doesn't need outer parentheses at top level
- ✅ cr eval 'range 3'
- ❌ cr eval '(range 3)' (adds extra nesting)
Let bindings: Use paired list format ((name value))
- ✅ let ((x 1)) x
- ❌ let (x 1) x (triggers "expects pairs in list for let" error)

Error Diagnostics

Type warnings cause eval to fail (intentional safety feature)
Check .calcit-error.cirru for complete stack traces
Use cr cirru parse-oneliner to debug parse issues

Query Examples

Use cr query examples to see usage examples:

cr demos/compact.cirru query examples calcit.core/let
cr demos/compact.cirru query examples calcit.core/defn

For markdown snippet validation (docs check-md), see CLI Options.

Calcit Guide