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egison v4.1.0 Release Notes

Release Date: 2020-10-14 // over 3 years ago

  • 🆕 New Features

    • ✅ Enabled user-defined infixes for expressions and patterns: https://egison.readthedocs.io/en/latest/reference/basic-syntax.html#infix-declaration
    • 👍 Allowed let expression to decompose data. Unlike match expressions (of Egison), this does not require matchers and the decomposition pattern is limited. > let (x :: _) := [1, 2, 3] in x 1 > let (x :: _) := [] in x Primitive data pattern match failed stack trace: <stdin>
    • Enabled data decomposition at lambda arguments. > (\(x, _) -> x) (1, 2) 1
    • Implemented partial application. > let add x y := x + y in map (add 1) [1, 2, 3] [2, 3, 4]
    • Huge speedup in mathematical programs:
      • Reimplemented math normalization, which was originally implemented in Egison, to the interpreter in Haskell.
      • Implemented lazy evaluation on tensor elements.
    • ➕ Added new syntax for symmetric / anti-symmetric tensors.

    Backward-incompatible Changes

    • 🔄 Changed the syntax to start definitions with def keyword.

      def x := 1

    • io was previously defined as a syntastic constructs, but it is changed into a primitive function. Namely, users will need to wrap the arguments to io in a parenthesis, or insert $ after io.

      -- Invalid
io isEof ()

    -- OK io (isEOF ()) io $ isEOF ()

    
### Miscellaneous
* ➕ Added a command line option `--no-normalize` to turn off math normalization implemented in the standard math library.
* ✅ Revived TSV input options: <https://egison.readthedocs.io/en/latest/reference/command-line-options.html#reading-tsv-input>
* 🗄 Deprecated `redefine`.