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Shard

Shard is a programming language designed for declarative builds and configuration of the Amethyst Operating System.

Shard is a...

  • declarative
  • pure
  • functional
  • lazy
  • dynamically typed

language majorly inspired by Nix and NixOS and is implemented as a strict superset of nix. It therefore shares most core principles with the well-established nix package manager and linux distribution.

TODO:

  • String interpolation
  • String interpolation in paths
  • String interpolation in attribute names
  • stack-overflow handling in the evaluator
  • == and != for lists and sets

Building

There are no dependencies other that libc to the pure implementation of shard.

To build the interpreter, just run make in this directory:

$ make

If successful, the interpreter binary will be placed in build/shard. It can be invoked using ./build/shard <file.shard>

Examples

There are a few example programs in the examples/ directory

Editor Support

TODO

Language Overview

Shard code Description
Basic values
true , false Boolean values
null Null value
69, 420 Integer values
3.1415 Float values
"Hello, World" String literal
"foo ${bar}" String interpolation
/path, ~/path, ./path Absolute and relative path literals
<path> Shard search path
Compound values
{ x = 69; y = 420; } Attribute Sets
{ x.y = 42; } Nested attribute sets
rec { x = 34; y = x + 35; } Recursive attribute sets
[ "foo" "bar" "baz" ] Linked lists
Prefix Operators
-number Numeric negation
!boolean Logical not
Infix Operators
bool || bool Logical or
bool && bool Logical and
bool -> bool Logical implication
expr == expr Equality
expr != expr Inequality
expr > expr, expr < expr, expr >= expr, expr <= expr Relational comparison (greater than, less than, ...)
set // set Attribute set combination
set ? attr Attribute check
set . attr [or value] Attribute selection
list ++ list List append
expr + expr Numerical or textual (string) addition
expr - expr Subtraction
expr * expr Multiplication
expr / expr Division
func expr Function call
Control Structures
if bool then "yes" else "no" Conditional/Ternary expression
case value of ... Case (switch) expression
assert value; "pass" Assertion check
let x = 34; y = 35; in x + y Let bindings
with set; value With expression -> Bind all attributes in a set to the current scope
Functions
x: x + 1 Function definition
x: y: x + y Curried function definition
{ x, y }: x + y Function definiton with set destructuring
{ x ? "foo" }: x Default attribute value
{ x, ... }: x + 1 Ignored additional attributes
{ x, ... } @ args: x + args.y Whole set binding to args
Builtins
TODO

License

Shard is a part of the Amethyst Operating System and is therefore licensed under the MIT license.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.