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%RED%This page is left here as a todo list, but not further maintained%ENDCOLOR%.

Last update of this page at %REVINFO{"$date"}%. The content of this page will partially move to the [[UhcUserDocumentation#LanguageImplementationStatus][status section of the ehc manual]].

These (currently incomplete) tables relate to the latest revision on the Subversion trunk, at the time of writing.

Y means a feature is present, Y/N (or YN) means work on it is underway but it is half-finished, N means it is not present but it will be, n ditto but one can live without, NN means it is  not present and most likely never will be. Please note [[FreqentlyAskedQuestions#Will_EH_syntax_support_feature_X][this answer in the FAQ]].

---++ Haskell 98 features

|*Feature*|*.eh status*|*.hs status*|
|Modules|NN|Y|
|Type synonyms|Y|Y|
|...with arguments|Y (use type lambdas)|Y|
|Infix operators at type level|NN|N|
|Turning infix type constructors into prefix type constructors|Y (use type lambdas)|N|
|newtype declarations|N|Y|
|n+k patterns|NN|NN|
|Prelude|NN|Y (details are missing)|
|deriving construct|NN|Y|
|default construct|N|N|
|Irrefutable patterns|N|Y/N|
|Automatic binding groups detection|N (each let forms a DIY binding group)|Y|
|Strictness flags|N|n|
|Literate Haskell source format|NN|Y/N (only \begin{code}...\end{code})|
|Infixity of operators influences parsing of expressions, as described in the report|NN|N|

---++ Extended features

|*Feature*|*.eh status*|*.hs status*|
|Type lambdas (undocumented?)|Y|N|
|Automatic destructor deriving|[[http://code.google.com/p/ehc/issues/detail?id=4&can=2&q=][buggy]]|N|
|Polymorphic kind inference|Y|Y|
|Explicit kinding|Y|Y/N|
|Explicit implicit parameters|Y|Y|
|Higher ranked polymorphism|Y|Y|
|Extensible records|YN|YN|
|Multiparameter type classes|Y|Y|
|Functional dependencies|N|N|
|Lexically scoped type variables|Y (introduced in patterns)|Y|
|Existential quantification|Y|Y|
|Partial type signatures (denotated with dots ...)|Y|Y/N|

Some combinations are not yet fully dealt with:

|*Feature combination*|*.eh status*|*.hs status*|
|Type classes & data types, eg data C a => D a = ...|YN|YN|
|Existential quantification over type classes, eg exists a.C a => a|YN|YN|
|Multiparameter type classes and quantification over subset of involved type variables|YN|YN|

---++ Runtime system, backend, and use

The runtime system (RTS) is independent of the frontend, so the status is not split up into .eh and .hs status.

|*Feature*|*status*|
|Separate compilation|Y|
|Mutual recursive modules|N|
|Integer type|Y (via [[http://www.swox.com/gmp/][GMP]])|
|Float types|Y|
|Exceptions|Y|
|Threads|N|
|Foreign function interface|Y/N|
|GRIN based C backend with global optimizations|Y/N|
|GRIN based [[http://www.llvm.org/][LLVM]] backend with global optimizations|Y/N|
|GRIN based C interpreter, per module compilation|Y|
|GRIN based interpreter (written in Haskell, for testing purposes)|Y|
|Garbage collection|Y ([[http://www.hpl.hp.com/personal/Hans_Boehm/gc/][Boehm GC]], EHC gc in development)|


---++ Current work [on/after 9 Jan 2008]

   * [[Atze.WebHome][Atze Dijkstra]]: Haskell frontend (in general: make it Haskell), GRIN based C interpreter
   * [[Main.JeroenFokker][Jeroen Fokker]]: GRIN backend
   * Arie Middelkoop: Ruler system
   * John van Schie: [[http://www.llvm.org/][LLVM]] backend

---++ Future work

Dynamic variables are partially implemented.

GADTs are not currently supported - but there is an experimental stage to support GADTs, which now needs updating to compile against the current codebase. Volunteers?