Evaluation

kesh is line-oriented.

Lines

• Code is evaluated line-by-line, top to bottom
• Lines are separated by either newline or comma ,
• There are two types of lines:
  1. Declaration lines
  2. Expression lines

Blocks

• A block {} consists of lines
  • Declaration lines
  • Expression lines
• A block's value is the value of its last evaluated expression line
• A block is itself an expression

Collections

• A collection [] consists of lines
  • Declaration lines in objects
  • Expression lines in other types
• Collection is a reference type

Tuples

• A tuple () consists of lines
  • Expression lines
• Tuple is a reference type, ideally it would have value semantics

Functions

• A function -> is a callable collection
• A function consists of parameters and a body
• Its parameters is the unpacking of its argument, as either a tuple or a collection
  • The unpacked argument's values are available to the function body's scope
• Its body is an expression, typically a block
• Function is a reference type

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Not exactly BNF:

block      > line (> declaration) > expression (> …)
collection > line (> declaration) > expression (> …)
tuple      > line > expression (> …)
function   > expression (> …)