Release 0.5

Curv Changes since Release 0.4

There are multiple language changes, with deprecation warnings for old
syntax. You should fix deprecation warnings now if you have old Curv code,
because the old syntax will be removed in a future release. By default,
deprecation warnings are throttled. Use curv -v to see all warnings.
Features marked experimental are unstable, subject to change.

Platform/Build Support

Curv 0.5 includes a prebuilt AppImage for Linux.

• @ComFreek -- Windows port.
• @zeeyang: automated MacOS build (using github actions)
• @A-G-D: automated AppImage build for Linux (using github actions)
• Apple Silicon support on Macintosh.
• AMD GPUs supported on Linux using AMD Mesa 19.x driver.
• documented/tested exporting images on a headless Linux server.
• make upgrade command

File Import/Export

• @Xiaoyuew -- Faster mesh export (multi-threaded, multi-core).
• @zeeyang: add jgpu export file format (GPU program as JSON)
• @zeeyang: add GLTF export file format
• @zeeyang: remove curvc (no longer being built)
• curv dirname reads a directory as a Curv program (directory format)
• JSON export no longer tries hard to distinguish JSON from non-JSON data.
  Non-JSON data is now exported as a string.
  #foo exports as "foo". sin exports as "<function sin>".

Command Line

• @A-G-D: filename now optional in curv -le, default is new.curv
• Configuration file ~/.config/curv contains defaults for -O options,
  is a Curv source file, a record containing {viewer,export} fields.
  See docs/Config.rst
• All -O option values are now specified as Curv expressions.
  Symbols used in -O options: -Ocolouring=#vertex or -Ocolouring=#face
• rename -Ocolour= to -Ocolouring=
• --depr= option controls deprecation warnings

REPL

• supports := (assignment) statement
• fully supports generator expressions
• help in REPL is extremely experimental, only partially implemented
• see docs/REPL.rst

Rendering in Viewer Window

• @zeeyang: improved raymarching (backup if overstep due to bad SDF)
• There are configurable render parameters. For a list, use curv --help.
  • You can set them on the command line using -Oname=value.
    What's new: value is an arbitrary Curv expression.
  • You can set them in the config file, in the viewer section. [new]
  • You can set them in a shape value by manually adding a render field
    to the shape structure. [new, experimental]
• new render parameters:
  • ray_max_iter, ray_max_depth: bug #78 [experimental]
  • shader -- lighting & shadow function for object surface [experimental]

Shape Library

• @lf94: add lib.builder with snowman example [experimental]
• @lf94: add soroban example
• @zeeyang: add 2D polyline primitive
• @zeeyang: add repeat_finite primitive
• capped_cone
• fix show_axes to preserve the bounding box
• generalized polygon primitive (can be non-convex, self-intersecting)
• lib.noise [experimental]
• a >> into union [b, c] means union [a, b, c]

Compiler and Interpreter

• general tail call optimization
• better compile/runtime error messages
• function names in stack traces
• SubCurv enhancements (more things that compile to GLSL shader language):
  • numeric matrix data types: 2x2, 3x3, 4x4
  • matrix multiplication (dot)
  • boolean vector types: bool2, bool3, bool4, bool32
  • boolean vector operations: and, or, xor, not
  • boolean matrix types: bool2x32, bool3x32, bool4x32
  • better support for parametric variables
• add docs/Implementation (source code structure, lang. implementation)

Curv Language

• Quoted identifiers: 'foo bar' is an identifier with an embedded space.
  'if' is an identifier, not a reserved word. '_ is an escape sequence
  representing a literal ' within a quoted identifier.
• Numbers
  • number patterns like 42 or -0.5
  • sign function returns -1, 0 or 1
  • sum added to SubCurv
• Lists
  • a++b infix list catenation operator
  • deprecate (a,b,c) list syntax; use [a,b,c] instead
• A string like "abc" is now a list of characters.
  Lists are heterogenous, so "abc" ++ [1,2,3] is a list of 6 elements.
  • #"a" is a character literal, and works as a pattern.
  • is_char x is true if x is a character value.
  • char converts an integer or list of integers to a character or string.
  • ucode converts a character or string to an integer or list of integers.
  • encode removed, replaced by ucode.
  • decode removed, replaced by char.
  • string converts an arbitrary value to a string.
  • new escape sequences in string literals: $_ -> $ and "_ -> "
• Symbols are abstract named values. They replace some uses of strings, but
  symbols are scalars, not lists. They replace 'enum' values in some languages.
  • #foo or #'hello world' is a symbol literal, which works as a pattern.
  • symbol function constructs symbol from string
  • is_symbol predicate.
  • true, false, null are now just aliases for #true, #false, #null
  • JSON export exports #true, #false, #null as JSON true, false, null.
  • Remove is_null predicate (breaking change).
• Data structure indexing
  • a.[i] is new array indexing syntax. a[i] is deprecated.
  • r.[#foo] is same as r.foo. Syntax r."foo" is deprecated.
  • a.foo.[i] := ... assignment statements
  • multi-dimensional array slicing using a.[indexlist1,indexlist2]
  • generalized index values (aka lenses, experimental):
    • a.[i] indexes a data structure with index value i
    • integers are index values (they index lists)
    • symbols are index values (they index records)
    • a.[[i1,i2,i3]] yields [a.[i1],a.[i2],a.[i3]]
    • a.[this] yields a`
    • a.[tpath[i1,i2]] yields a.[i1].[i2]
    • a.[i1,i2] is a multidimensional array slice,
      short for a.[tslice[i1,i2]].
    • amend index newelem tree is pure functional update,
      like tree.[index]:=newelem without the side effect.
• Functions:
  • is_fun deprecated, replaced by is_func and is_primitive_func
  • error is a function value (previously was magic syntax)
  • id -- identity function
  • identity renamed to idmatrix
  • compose is generalized to work correctly on partial functions
• Boolean array operators.
  • SubCurv supports new types Bool32, Bool[2-4], Bool[2-4]x32
  • experimental boolean array operations (also in SubCurv):
    • float_to_bool32, bool32_to_float
    • nat_to_bool32 (in SubCurv, argument must be a constant)
    • bool32_to_nat (not in SubCurv)
    • bool32_sum, bool32_product
    • lshift, rshift
  • vectorized boolean not function; unary ! operator is deprecated
  • vectorized boolean reduction functions and, or, xor
  • vectorized: <, <=, >, >=, bit
  • select [experimental]
• parametric records have a call field that reruns the constructor
  with different parameter values. The result is another parametric record,
  also with a call field.
• test definitions, for unit tests in a module, or anywhere else
• sc_test statement, for unit testing SubCurv [experimental]
• assert_error statement, for writing unit tests
• comma separated definition lists in let ... and {...}.
  Previously only ; was allowed as separator.
• in a statement context, () and (a,b,c) are generators.
• where is deprecated, use let instead.
• in a dynamic record literal, [#a,1] is equivalent to a:1, both expressions
• locative!func1!func2 is a statement, mutates a local variable by
  applying one or more functions to the contents.
• deprecate "foo":expr, in expression or pattern context.
• until clause for early exit from a for loop
• var definitions are deprecated, use local definitions instead.
• local <definition> is a generalized local definition, with sequential
  (not recursive) scope. Legal in any imperative context: do expression,
  compound statement, list constructor, dynamic record constructor.
• Only definitions are permitted in the head of a let or in a module
  (not actions). Use test definitions to add unit tests to a module.
• Remove 'generalized do'. Only do expressions are supported.
• fewer levels of operator precedence:
  • unite Power with Unary; not a breaking change; grammar becomes more liberal.
  • unite Relation with Range, breaking change, parse error for 1..3==[1,2,3]