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@rmartinho
Last active Oct 10, 2015
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Halcyon

This document is an informal collection of design ideas for the Halcyon programming language. This document in in permanent draft status; do not take anything you read here as final. There are no plans to ever actually implement the ideas here; they're listed only for future reference.

Wants

  • Static, strong typing

    Type errors at runtime are stupid.

  • Type inference

    Having to type types that the compiler knows is stupid.

  • First-class monadish things

    Something along the lines of F# computation expressions. I think I'll call them "environments".

  • Compile-time metaprogramming/code generation

    Syntactic and semantic manipulations are cool. I'm thinking of stuff along the lines of boo's syntactic macros, AST attributes and metafunctions; not along the lines of Ruby-style metaprogramming or C++ template metaprogramming.

  • Proper Unicode support

    "Are Halcyon strings UTF-8 or UTF-16?" is a question that makes no sense. Halcyon strings are sequences of codepoints, not code units. By that I don't mean they're UTF-32; saying they're UTF-32 makes as much sense as the question above: zero.

  • Proper iteration

    Only three loops are needed: while, do-while, and Python-like for-in. C#-like iterators or Python-like generators or any other yield-like construct does wonders with for-in.

  • Fundamental types in all shapes and sizes

    Integers can be signed or unsigned, and can have 8, 16, 32, 64, or 128 bits. Floating point numbers can be binary 16-, 32-, 64-, 80-, or 128-bit; or decimal 32-, 64-, or 128-bit. Machine word sized integers also exist in signed and unsigned variants. And hardware sized floats as well.

  • Bigints and multiple-precision floats

    The last option on the zero-one-infinity rule.

  • Unit type

    Everything has a value, even if a meaningless one.

  • Modules

    A nice module system is nice.

  • Purity

    Maybe D-like, in that only observable purity is required.

  • Number theory concepts

    Rings, groups, etc, can be defined by types. This is the basis for things like operator +.

  • Proper resource handling

    As in C++ style scope based resource management.

Don't wants

  • Octal or binary literals

    Octal is only ever useful for chmod. Binary is hardly useful for anything over 8 bits. Hexadecimal should cover everyone's needs. Write a syntactic extension if you desperately want binary or octal literals.

  • Support for anything other than x86 and ARM

    If it forces me to make the language any more complex than I want, I don't care about your platform.

  • void

    A function that returns nothing? Sorry, but no. Return unit, it's implicit.

  • Global namespace

    Namespace all the things

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