Claro is a small, readable scripting language designed to help beginners — especially learners with learning disabilities — learn programming without being overwhelmed by punctuation-heavy syntax.

Claro stays plain-text first: simple enough to start with SET name "Jon", but able to grow into stronger typed scripts, objects, packages, networking, and tooling over the v1 line. Graphics/SDL work is experimental and not enabled in the stable executable.

Status

Current release: Claro v1.18.26

Validated in this package:

./claro --version
# Claro v1.18.26

./claro test
# PASS: 0 failure(s)

./claro validate
# Validation passed. Claro v1.18.26 networking reliability is ready for use.

python3 tools/validate_typecheck_diagnostics.py
python3 tools/validate_version_convention.py
python3 tools/validate_package_security.py
python3 tools/validate_ci_workflow.py

Beginner-first syntax

Claro accepts both the sentence-like style and the shorter simple style:

SET name TO "Jon"
SET name "Jon"
SET city to "Edmonton"

ASK "What is your name?" name
SAY "Hello " + name

IF name = "Jon"
    SAY "Nice name!"
END

Older forms such as ASK "Name?" AS name, ENDIF, DONE, and LEARNED still work so older Claro examples do not break.

Simple functions

TEACH greet name
    SAY "Hello " + name
END

DO greet "Jon"

Older function syntax still works:

TEACH greet TAKES name
    SAY "Hello " + name
LEARNED

CALL greet WITH "Jon"

Objects and classes

Classes can have typed fields and simple methods.

CLASS Player
    HAS name TEXT
    HAS score NUMBER

    TEACH show
        SAY name
        SAY score
    END

    TEACH add points
        SET score score + points
    END
END

NEW Player player
SET player.name "Jon"
SET player.score 10
SET player.score player.score + 1

DO player.show
DO player.add 5
SAY player.score

Object helper commands:

OBJECT CLASS player AS kind
OBJECT FIELDS player AS fields

Static type safety

Beginners can still write the simplest form:

SET name "Jon"

When learners are ready, Claro can protect variables with plain-text types:

SET score NUMBER 10
SET name TEXT "Jon"
SET ready YESNO YES

TYPE OF score AS kind
SAY kind

CHECK TYPE score IS NUMBER

Advanced container checks are available through claro typecheck:

SET names AS LIST OF TEXT TO LIST
ADD "Ada" TO names

SET scores AS MAP OF NUMBER TO MAP
PUT scores KEY "math" VALUE 98

claro typecheck also has an early function-argument diagnostic foundation. A function can state a parameter expectation with CHECK TYPE, and calls with the wrong value type or a missing checked argument get a friendly error:

TEACH square amount
    CHECK TYPE amount IS NUMBER
    SAY amount
END

DO square "oops"

Type mismatch for function square: parameter amount needs NUMBER, but this argument looks like TEXT.
Function square needs argument amount as NUMBER, but this call does not provide it.
Function greet needs 1 argument, but this call gives 0. Add the missing argument.
Function square only accepts 1 argument, but this call gives 2. Remove the extra argument.
Function squre is not known yet. Check the function name or add TEACH squre before calling it.

The unknown-function diagnostic is validated for both modern DO squre 4 and compatibility CALL squre WITH 4 calls. Compatibility calls that leave WITH empty, such as CALL greet WITH, now count as zero arguments, so learners get the same missing-argument guidance as DO greet instead of the checker treating the blank as an argument.

For functions with more than one checked parameter, Claro reports each mismatched argument with the parameter name:

TEACH label TAKES name, age
    CHECK TYPE name IS TEXT
    CHECK TYPE age IS NUMBER
END

CALL label WITH 7, "old"

The same narrow diagnostic foundation now covers simple object method calls when the object was created with NEW and the method body uses CHECK TYPE for a parameter. Correct calls such as DO player.add 5 and compatibility calls such as CALL player.add WITH 5 are covered by validation, and wrong-type calls get a focused learner-facing error. This also works when the checked method appears after another method in the same class, so normal multi-method class examples still get the same wrong-type and extra-argument guidance:

CLASS Player
    HAS score NUMBER

    TEACH add points
        CHECK TYPE points IS NUMBER
        SET score score + points
    END
END

NEW Player player
DO player.add "five"
CALL player.add WITH "five"

Type mismatch for method Player.add: parameter points needs NUMBER, but this argument looks like TEXT.
Method Player.add needs argument points as NUMBER, but this call does not provide it.
Method Player.rename needs 1 argument, but this call gives 0. Add the missing argument.
Method Player.add only accepts 1 argument, but this call gives 2. Remove the extra argument.

If a learner calls a simple object method before creating the object with NEW, claro typecheck now points to the missing setup instead of letting the dotted call look like an ordinary unknown function. This covers both the modern DO player.add 5 form and the older compatibility CALL player.add WITH 5 form, including CALL mistakes where the method name itself is wrong:

Object player is not known yet. Create it with NEW ClassName player before calling player.add.
Object player is not known yet. Create it with NEW ClassName player before calling player.fly.

If the object exists but the class does not declare that method, Claro now names the class and suggests where to add the missing TEACH block. This is validated for both modern DO player.fly 5 and compatibility CALL player.fly WITH 5 calls:

Object Player has no method fly. Check the method name or add TEACH fly inside CLASS Player.

For simple object fields created with NEW Class name, claro typecheck also catches direct wrong-type field assignments such as SET player.score "ten" when the class says HAS score NUMBER. This remains true if the HAS field appears after a simple method in the class, so learners get the field-type error instead of a misleading unknown-field hint:

Type mismatch for field player.score: expected NUMBER, but this value looks like TEXT.

It also catches direct assignments to undeclared fields and suggests the matching HAS line:

Object Player has no field level. Check the field name or add HAS level NUMBER to the class.

The same check follows simple arithmetic and text-concatenation expressions. For example, SET player.score player.name + 1 reports that the value looks like TEXT, rather than silently accepting an expression whose result cannot fit the NUMBER field.

TEXT-valued and YESNO-valued field-name mistakes are validated too:

Object Player has no field nickname. Check the field name or add HAS nickname TEXT to the class.
Object Player has no field ready. Check the field name or add HAS ready YESNO to the class.

If Claro cannot infer the value type for an undeclared field yet, it avoids exposing the internal ANY placeholder and keeps the hint beginner-facing:

Object Player has no field level. Check the field name or add the field to the class with the right type.

Direct object-field CHECK TYPE metadata mismatches are validated for NUMBER, TEXT, and YESNO fields too. For example, after HAS ready YESNO and SET player.ready YES, CHECK TYPE player.ready IS TEXT reports:

Type check failed: expected TEXT, but player.ready looks like YESNO.

If CHECK TYPE names an undeclared field, Claro now gives the same class-and-field hint as direct field assignment. For example, CHECK TYPE player.level IS NUMBER after NEW Player player reports:

Object Player has no field level. Check the field name or add HAS level NUMBER to the class.

TEXT expectations are validated with the same pattern, for example CHECK TYPE player.nickname IS TEXT reports:

Object Player has no field nickname. Check the field name or add HAS nickname TEXT to the class.

YESNO expectations are validated too; CHECK TYPE player.enabled IS YESNO reports:

Object Player has no field enabled. Check the field name or add HAS enabled YESNO to the class.

If a learner checks a field before creating the object with NEW, claro typecheck points to the missing object setup:

Object player is not known yet. Create it with NEW ClassName player before checking player.score.

The same missing-object guidance is now validated for direct field assignment before NEW:

Object player is not known yet. Create it with NEW ClassName player before setting player.score.

Project and package workflow

v1.18.26 hardens Claro's project/package workflow.

Create a starter project:

claro new MyProject
cd MyProject
claro run

Manage packages:

claro package init
claro package add text
claro package list
claro package remove text
claro package doctor
claro package lock

Claro now creates and maintains:

claro.project
claro.lock
packages/

claro package doctor also checks that every listed package has a manifest whose name: matches the package name in claro.project; a mismatch is reported as BAD package manifest name instead of being treated as a healthy package. It also compares the complete checksum: field, so extra or trailing checksum text, or a duplicate checksum field, is rejected as BAD package checksum. Package manifests must contain exactly one version: 1 field; duplicate or prefix-matching values such as version: 10 are rejected as BAD package version. The project manifest must contain exactly one manifest-version: 1 field; duplicate or prefix-matching values such as manifest-version: 10 are rejected as BAD project manifest version: expected 1. It must also contain exactly one non-empty name: field; otherwise doctor reports BAD project manifest name: expected a non-empty name.

Starter projects created with claro new MyProject use the same manifest-version: 1 and lock-version: 1 headers as claro package init, so the first project files match the package maintenance tools.

Project names and package names are checked so unsafe names such as ../bad are rejected before Claro creates folders. Names must also be 64 characters or fewer, which keeps generated project and package paths predictable. If an unsafe package name is already present in claro.project, claro package doctor, claro package lock, claro package list, claro package init, claro package add, and lockfile refreshes during claro package remove flag it instead of treating it as safe lockfile data. claro package remove can also remove the exact unsafe entry, so a learner can repair a bad project file without Claro using that unsafe name as a folder path. claro package doctor also verifies listed package lockfile checksums, reports stale lock entries, and rejects lockfile package entries that are not listed in claro.project.

Standard-library path and collection helpers

Claro includes tested, namespaced helpers for everyday programs:

IMPORT "lib/path.claro" AS path
IMPORT "lib/collections.claro" AS collections

CALL path.join WITH "notes", "today.txt"
SAY RESULT

SET names AS LIST OF TEXT TO LIST
ADD "Ada" TO names
ADD "Grace" TO names
CALL collections.join WITH names, " and "
SAY RESULT

The path module includes join, basename, dirname, ext, stem, and absolute. The collections module includes list length/search/join/reverse helpers and map key/value/default-access helpers. See docs/STDLIB.md for the complete, current API.

Networking

v1.18.26 adds safer beginner networking commands with offline claro:// test URLs.

HTTP CHECK "claro://hello" AS safe
SAY safe

HTTP GET "claro://hello" AS page STATUS status
SAY page
SAY status

HTTP SAVE "claro://json" TO "network_demo.json" AS saveStatus
SAY saveStatus

The latest HTTP status is also stored in LASTHTTP. Real http:// and https:// requests use curl when available, while claro:// works offline for lessons and tests.

Useful commands

claro help
claro --version
claro test
claro validate
claro doctor
claro examples
claro check examples/quiz.claro
claro typecheck examples/type_hardening.claro
claro fmt examples/quiz.claro
claro repl
claro new MyProject
claro run
claro package init
claro package add text
claro package list
claro package doctor
claro ide

Good first scripts

./claro lessons/01_hello.claro
./claro examples/quiz.claro
./claro examples/simple_functions.claro
./claro examples/objects_classes.claro
./claro examples/text_polish.claro
./claro examples/networking.claro

Documentation map

If you are new to Claro, start here:

docs/QUICK_START.md
docs/FIRST_HOUR.md
lessons/README.md
docs/CLI.md
docs/CURRENT_STATUS.md

Feature references by current status:

Ready for beginner lessons: language reference (docs/SPEC.md), friendly errors/checking (docs/ERRORS.md, docs/LINTER.md, docs/TESTING.md), formatter (docs/FORMATTER.md), and simple functions (docs/SIMPLE_FUNCTIONS.md).
Foundation present, still being polished: static typing (docs/ADVANCED_STATIC_TYPING.md), objects/classes (docs/V1_15_OBJECTS_CLASSES.md), local projects/packages (docs/V1_16_PACKAGES_PROJECTS.md), HTTP client networking (docs/V1_17_NETWORKING.md), cooperative tasks (docs/CONCURRENCY.md), and IDE metadata/helper support (docs/IDE.md).
Planned or experimental, not stable beginner features yet: remote package registry (docs/PACKAGE_REGISTRY.md), web server API (docs/WEB_SERVER_PLAN.md), full editor extension/LSP (docs/EDITOR_EXTENSION_PLAN.md), and real SDL graphics (docs/GRAPHICS.md, docs/SDL12.md).
Roadmaps: docs/ROADMAP.md for the current v1 direction and docs/COMPLETE_PLATFORM_ROADMAP.md for the larger platform goal.

Historical release notes and validation logs are kept in files such as docs/RC*_NOTES.md, docs/RC*_VALIDATION.md, and older docs/V1_*_VALIDATION.md. They are useful for project history, but they are not the beginner starting path.

Release direction

Claro should remain in the v1.xx.yy line for normal development. A future Claro v2 should mean a full rewrite years later, not an ordinary feature update.