Migration Guide for the New Syntax

Automated translation with egison-translate

We have a tool to help users convert old Egison programs into the new syntax. egison-translate automatically translates Egison programs in the old S-expression syntax into the new Haskell-like syntax. It can be built from the source as follows.

$ git clone git@github.com:egison/egison.git
$ cd egison
$ stack init
$ stack build --fast
$ stack exec -- egison-translate name-of-file-you-want-to-convert.segi


egison-translate does not preserve comments and shebangs. Please manually add them after the translation.

Changes in function names

Apart from the changes in the syntax itself, some of the library/built-in variable names have also been renamed to match the new syntax. All of these changes are supported in egison-translate.

Changes in naming rules

The following describes the changes in the naming rule of variables. The table shows the example of such changes and the detailed description is given under the table.

  Old name New name
1 take-while takeWhile
2 even? isEven
3 member? member
4 delete/m deleteAs
  1. Names connected with hyphens - are converted into camelCase.
  2. Unary function names that ended with a question mark ? is prefixed with is.
  3. Non-unary function names that ended with a question mark foo? now omits the last question mark.
  4. Function names of the form foo/m are renamed as fooAs. For instance, delete/m became deleteAs.

Instance-wise changes

Also, some of the Lisp-inspired names have been renamed into Haskell-like names as shown in the following table.

Old name New name
car head
cdr tail
rac last
rdc init