• Introduction
• Editing in Haskell mode
• Completions
• File marking
• Declarations parsing
• Console
• Key bindings
• Literate Haskell
• Known problems
• License and Disclaimer

Introduction

• syntax coloring ;
• keywords completion ;
• electric completion for some structures (like case, if, let etc.) ;
• functions marking ;
• marking of class, data, import, instance, newtype, and type declarations.

Editing in Haskell mode

• if the file has a .hs or .lhs extension, it will automatically be opened in Haskell mode.
• if the first line of the file is

      #!/usr/bin/env runhaskell
  

  or any other path ending with the term runhaskell, it will also automatically be opened in Haskell mode.
• you can manually select Haskell mode from the Modes popup (🄼) located in the control bar of the document window.

Completions

• you can type the first letters of a keyword (like deriving, infix, qualified etc.) and hit the completion key (usually F1 or ⌃-Tab). Alpha will complete the word automatically.
• for the structure keywords, you can hit the completion key just after the word and Alpha will insert a complete template for the corresponding structure. For instance: type "if" followed by the completion key in order to insert

  if *
  then *
  else
  *
  

  where the asterisk denotes an insertion bullet. You move from an insertion bullet to the next one with the Tabulation key.

File marking

foo :: (Num a) => a -> a -> a
foo x y = 2*x+3*y

Declarations parsing

Console

-- Welcome to Alpha's Haskell console.
-- Running ghc 8.6.5.
λ> :show imports
import Prelude -- implicit
λ> map (+3) [2,6,7,1]
[5,9,10,4]
λ> :info filter
filter :: (a -> Bool) -> [a] -> [a] 	-- Defined in ‘GHC.List’
λ> filter even [1..10]
[2,4,6,8,10]
λ> 

Key bindings

• Cmd-K to switch to Alpha's Haskell console.
• Ctrl-Cmd-C to insert code environment.
• Ctrl-Cmd-P to insert '> ' code prefix.
• Ctrl-Opt-Cmd-P to remove '> ' code prefix.
• Ctrl-Cmd-R to render in Markdown viewer.
• Cmd-L to reload the current set of modules.
• Cmd-E to go to the last error in the console.

Literate Haskell

Insert Code Environment

This command is suitable for Latex-style literate programming. It lets you insert a \begin{code}...\end{code} environment. If there is a selection, it is wrapped in the environment.

Insert '>' Prefix

This command is suitable for Bird-style literate programming. It lets you insert a '> ' prefix at the beginning of the selected lines.

Remove '>' Prefix

This command appears when you open the menu and press the Option key (⌥). It removes the '> ' prefix found at the beginning of the selected lines.

Render Markdown

This command lets you visualize the contents of the literate Haskell file in Alpha's Markdown viewer.

Known problems

License and Disclaimer

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• Neither the name of Bernard Desgraupes nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.