agda-kernel

An experimental Agda kernel for Jupyter. Used at Nextjournal [nextjournal kernel].

Examples

You can launch the following examples directly via the mybinder interface:

• example/LabImp.ipynb [binder].

Alternatively, if you have binder, then you can use repo2docker locally:

repo2docker https://github.com/lclem/agda-kernel

Installation

pip install agda_kernel
python -m agda_kernel.install

Syntax highlighting

Syntax highlighting is done separately by Codemirror, but unfortunately there is no Agda mode packaged with it. A rudimentary Agda mode for Codemirror can be found in codemirror-agda/agda.js. In order to install it, type

make codemirror-install

Agda extension

In order to improve the Jupyter interface, it is strongly recommended to also install agda-extension.

Functionality

Each code cell must contain a line of the form module A.B.C where. For instance:

module A.B.C where

id : {A : Set} → A → A
id x = x

Upon execution, the file A/B/C.agda is created containing the cell's contents, and it is fed to the Agda interpreter (via agda --interaction). The results of typechecking the cell are then displayed.

After a cell has been evaluated, one can

• Run Agsy (auto) by putting the cursor next to a goal ? and hitting TAB. The hole ? is replaced by the result returned by Agsy, if any, or by {! !} if no result was found. If there is more than one result, the first ten of them are presented for the user to choose from.

• Refine the current goal by putting the cursor next to a goal {! !} and hitting TAB. An optional variable can be provided for case-splitting {! m !}.

• Show information about the current context, goal, etc.: putting the cursor near a goal/literal and hit SHIFT-TAB.

Editing

Inputting common UNICODE characters is facilitated by the code-completion feature of Jupyter.

• When the cursor is immediately to the right of one of the base form symbols hitting TAB will replace it by the corresponding alternate form. Hitting TAB again will go back to the base form.

base form	alternate form
->	→
\	λ
<	⟨
B	𝔹
>	⟩
=	≡
top	⊤
/=	≢
bot	⊥
alpha	α
/\	∧
e	ε
/	∨
emptyset	∅
neg	¬
qed	∎
forall	∀
Sigma	Σ
exists	∃
Pi	Π
[=	⊑