Coco

is a CoffeeScript dialect that aims to be more radical and practical.

Why

On its way to hide JavaScript's bad parts, CoffeeScript has accumulated own quirks: horrible variable scope, awkward ranges, confusing and/or pointless keywords, verbose file extension, and so on. Coco tries to amend them, entwining good parts of both.

Principles

• Respect JS semantics and idioms.
• Die for DRY.
• Perl over Ruby.
• Fewer keywords, punctuations and runtime errors.

Differences

• Improvements
• Incompatibilities
• Side by Side Comparison

Documents

• Additions
• Glossary
• Annotated Source

Installation

Get Node.js and npm, then:

• npm i -g coco
• git clone git://github.com/satyr/coco.git && cd coco && bin/coke i

Changelog

0.9.1

• Added if-block. (#151)
• Added for-let. (#164)
• Added <> aka lef. (#180)
• Gave |> the lowest precedence.
• Made block constructions directly dot-accessible.
• Made JS literal Markdown-esque. To include N `, close with N+1 `: ``` '``' ```
• Quit reusing temporary variables.
• File extensions like co.json, coon, or cocoon now imply --json.
• Fixed:
  • #193
  • #195
  • #199
  • #200
  • gkz/LiveScript#273
  • gkz/LiveScript#279

0.9.0

• Literal & is now used to reference several new targets:
  • Left hand of |> (in place of _).
  • Current item of newly added quick map: for [0 1] => &+2 # [2 3]
  • Subject of new with as proposed in #172.
• Made cascade, now with in disguise, require at least one & in body. (#179)
• Made let accept this = on the first assignment to substitute old with.
• Made bodyless catch return the catchee.
• Made by -1 implied on downward ranges.
• Made interpolation apply to #& and #@.
• Quit expanding super followed by :: to parent method, so that call to super::anotherMethod works as expected.
• Fixed:
  • #175
  • #178
  • #185
  • #190
  • #192
  • coffee#1188

0.8.2

• Fixed:
  • #165
  • #168
  • coffee#2496
  • coffee#2506

0.8.1

• Fixed #162.

0.8.0

• Allowed hyphenated alphabets within identifiers as alias to their upper case: encode-URI-component => encodeURIComponent
• Added cascade. (#72
• Changed the pipe operator to |>.
• Revised => as another block creation operator.
• export/import/const/var can now appear anywhere.
• catched variables are now function-scoped. (coffee#2422)
• Generated variables now get postfix $ rather than prefix __.

0.7.6

• Added export const.
• Enabled object splat within brace objects via ...:.
• Allowed array repetition to work on slices and comprehensions.
• Disallowed malformed hex/unicode escape sequence in string.
• Quit overloading + for array concatenation.
• class can be bodyless again.
• super no longer auto-.calls more than once.

0.7.5

• Implemented implements. (#144)
• Top-level voids are now simply ignored and usable like Python's pass.

0.7.4

• Added import declaration in place of the implicit this import: import a, b => this <<< a <<< b
• Made super work in accessor methods.
• Disallowed redeclarations via var.
• Improved handling of nonexistent files.

0.7.3

• Node.js 0.8.x.
• Added const and var. (#139)
• Made function variables read-only.
• Removed -n shorthand for --nodejs. (#142)
• Bug fixes:
  • super with nested classes and methods
  • f a, while b then c etc.
  • and others: #138 #141 #143

0.7.2

• Revised accessor. (#5)
• Allowed implicit array after some unary operators.
• Added named backcall: <-:f g => g(:f ->)
• Made {[q]:p} short for {p: [q]:p}.

0.7.1

• Added export statement. (#121)
• Made {{q}:p} short for {p: {q}:p}.
• Allowed keyword literals as object shorthand: {true} => {true: true}
• Allowed decimals and $ in number comments.
• Removed uppercase radix prefixes and exponential notation as per coffee#2061.
• Labelling a function (literal or IIFE sugar) now names it. E.g. :f -> compiles to (function f(){}).
• super call to a bound class now works as expected.
• All compiler-generated variables are now double-underscore prefixed.
• --interactive no longer implies --bare. Use -bi when you want top-level variables to persist.

0.7.0

• Caught up Node.js 0.6.x.
• ! against function/backcall now suppresses its auto-return.
• superclass now points to the constructor that the class extends.
• super now relies solely on superclass rather than requiring special forms like C::m = ->.
• of no longer delegates to Array::indexOf, making it consistent with for-of behavior.
• Inline implicit objects now close at newline or if/for/while/until.
• --print no longer implies --compile.
• --watch now works on Windows.

0.6.7

• Fixed coffee#1715 etc.
• Trivial improvements.

0.6.6

• Added unary assignments: !! = x => x = !!x
• Made a? <<< b short for a <<< b if a?.
• Improved stack traces from directly run .co files.

0.6.5

• case/of/instanceof now works better with array slice.
• instanceof now rejects invalid right operands.

0.6.4

• Unary operators now spread into an array operand: +[a, b] => [+a, +b]
• .. now points to the constructor under class.
• coke now works from subdirectories. (coffee#1687)

0.6.3

• Added pipe operator: f! => g _ => _ = f!; g _
• Fixed identifier lexing as per ES5.
• Improved label handlings.
• Helper functions are now declared last. (coffee#1638)

0.6.2

• Added character ranges: [\a to \d] => [\a \b \c \d]
• Added named destructuring: {p, q}:o = f! => o = f!; {p, q} = o
• Numbers can no longer start with ..
• function can no longer prefix ->/~>. Use ~function to declare bound functions instead.

0.6.1

• Allowed line folding after for prepositions.
• importing onto a soaked expression is now safe.
• --json now modifies --ast or --compile.
• Fixed #81 etc.

0.6.0

Additions

• Added soak assign.
• Added <? and >? operators.
• Loops can now have else clause.
• import x is now short for this <<< x.
• , after (, [ or another , now implies void.

Changes

• Added object slice.
• Added bang call: f! => f()
• Revised clone syntax from x{} to ^x.
• Revised semiautovivification syntax from .!/.@ to .@/.@@.
• Variable interpolations no longer require braces: "(#id)" => "(" + id + ")"
• Spaced dots now close implicit calls. See coffee#1407.
• Direct calls to super now delegate this.
• extended hook is back.
• from of for is now optional, meaning from 0. tilless from is no longer allowed.

0.5.4

• while/until can now have update clause after test clause: continue while f(), g() => for (; f(); g()) {}
• that no longer triggers anaphoric conversion under unless/until.
• Disallowed a.=b = c p:~ (a, b) -> f ..., a etc.
• Fixed coffee#1416.

0.5.3

• Added do-while/until construction.
• Added $ flag to regexes. Same as .source, but more efficient.
• Suppressed implicit return on newed/setter functions.
• Sped up lexer.

0.5.2

• Added !? (inexistence) operator.
• function no longer requires parens around parameters.
• class block is now mandatory.
• Bug fixes: coffee#1352 coffee#1354

0.5.1

• a.b.c?.=d.e now works as expected.
• a[b, c] = d now works as expected.
• extras/coco.js works again on WSH.
• --output implies --compile again.

0.5.0

• Added ** operator.
• Overloaded +/-// (in addition to *) for arrays and strings.
• Revised let: let (a) ~> => let a then
• Allowed underscores within number literals.
• Major regex changes:
  • Dieted heregex: /// re /// => // re //
  • Allowed leading whitespace in normal regex literals when unambiguous.
  • No longer accepts invalid regexes.
• -> is now optional when function is used.
• case accepts comma-separated tests again.
• return/throw can now take a block.
• REPL now uses ^J to continue lines.

0.4.2

• Enabled:
  • ADI on ?.
  • ACI on ++/--
  • conditional destructuring assignments
  • colors and tab completion in REPL
• Made leading *s serve like list markers.

0.4.1

• Added string/array multiplication.
• Added label support.
• Aliased constructor as ...

0.4.0

• Added let. Unary do is back at being simple call.
• Added with.
• Added semiautovivification.
• Made :: a pure sugar for prototype, which can now directly refer to @:: under class body.
• ?. can now appear anywhere a normal dot can be used.
• ~. is changed to . ~.
• new no longer accepts splatted arguments.
• --interactive now works with --compile and --bare.
• Renamed --nodes option and .nodes method to --ast/.ast.
• Fixed the performance bug wrt long method chains.
• Quit supporting Node.js 0.3.x or lower.

0.3.2

• Unrestricted ADI for identifiers beyond @ and ::.
• Expanded property shorthands beyond @foo.
• Added typeof!, which inspects the internal [[Class]] property.
• Added shebang support.
• REPL results now evaluate more intuitively.
• Disallowed whitespace mixup for indentations.

0.3.1

• debugger now works anywhere.
• Revised heregex flag syntax: ///#{x}#{y}///? -> RegExp('' + x, y);
• Removed Coco.eval.
• Made extras/coco.js work as a mini-compiler on WSH.
• Added extras/mode-coco.js, an editing mode for Ace.
• Added --json option.

0.3.0

Pure Additions

• Added backcall, a sugar to flatten nested callbacks.
• do block can now work as a pair of normal parentheses.
• Improved ACI (automatic comma insertion): f {} [] x -> f({}, [], x);
• Improved ADI (automatic dot insertion): @@0'!' -> arguments[0]['!'];
• Multiline block on the RHS of object property now works as an implicit array.
• Heregexes now support dynamic flags: /// x #{? y } /// -> RegExp('x', y);
• Enabled compound accessigns: a.+=b -> a += a.b;
• ... in array destructuring (same as ...[]) now skips items rather than sliceing them. (coffee#870)
• Compilation errors now report line numbers.
• Coco object now emits more events for use with --require.

Incompatible Changes

• => -> ~>
• &. -> ~.
• Braceless objects no longer consume property shorthands. (coffee#618)
• Indentations within non-here strings are now stripped.
• Fixed block comment syntax to good ol' /* */.
• @0 is now this[0] rather than arguments[0].

0.2.2

• is not is the new isnt.
• @'++' is now valid as a shorthand for @['++'].
• Commas between primitive values are now optional.
• coke now automatically aliases tasks.
• extras/coco.js now works as a Gecko JS Module.
• Grouped documentation suite into doc/ for portability.
• Rewrote src/optparse.co.

0.2.1

• Added numeric ranges.
• Destructuring assignments can now specify default values using logical operators. Default arguments syntax has been changed accordingly. ((a || b) -> instead of (a ||= b) ->)
• do now performs special conversions against function literals with parameters, making it work as pseudo-let and Coffee 1.0.0 compliant.
• Allowed for i from x then as a sugar for for i from 0 til x then.
• Disallowed duplicate formal arguments.
• Improved syntax-highlight in src/index.html.

0.2.0

• Version bump for Xmas, in concert with Coffee 1.0.0.
• @@ is now a shorthand for arguments.
• do can now indicate a call against indented arguments.
• and and or now close implicit calls, making you write even less parens: f x and g y or z -> f(x) && g(y) || z;
• catch's variable declaration is no longer required.
• a<[ b c ]> is now equivalent to a[\b, \c] (was a(\b, \c)).
• case now requires brackets to have multiple conditions.
• Added --nodejs option. See coffee#910.
• Renamed --stdio to --stdin.

0.1.6

• Added character/word literal: \C + \++ -> 'C' + '++';
• Retrieving multiple properties at once is now possible: a[b, c] -> [a[b], a[c]];
• Destructuring into an object's properties is now possible:
  • a[b, c] = d -> a[b] = d[0], a[c] = d[1];
  • a{b, c} = d -> a.b = d.b, a.c = d.c;
• Compound assignments can now destructure: [@a, @b] /= c -> this.a /= c[0], this.b /= c[1];

0.1.5

• Conditional control structures can now be anaphoric; that within if, while or case block now refers to the condition value.
• Decimal numbers can now have arbitrary trailing alphabets as comments. e.g. 9times, 1.5s
• Added <<</<<<< as aliases to import/import all
• non-ASCII identifiers are now allowed.

0.1.4

• . and its families can now be used with numbers and strings, instead of []. a.0.'0' compiles to a[0]['0'].
• Added syntax for cloning objects; obj{key:val} acts like a simple version of ES5 Object.create, creating a prototypal child of obj and assigning to .key with val.
• default arguments can now choose to use ||/&&.
• super under a class block now refers to the superclass.
• .coffee extension is no longer supported.

0.1.3

• Compilation now prefers single quotes.
• AST now compiles faster, roughly 1.4 times than 0.1.2.
• []/{} can now be safely used as an placeholder within array destructuring.
• Improved --nodes output.

0.1.2

• ... is now prefix.
• {0: first, (*-1): last} = array now works.
• Added --lex to the coco utility. Removed --lint.
• src/ now has doc view.

0.1.1

Release.