dierk/fregegoodness

Source of the Frege Goodness gitbook

fregegoodness's Issues

Explain FregeFX

we may want to wait for the finalization of the native API but we may also just go ahead with what we have

Is "More Advanced Polymorphism" Ready?

I found that we have one more chapter titled "More Advanced Polymorphism" (the filename is higher-kinded.adoc,) nevertheless it have not linked from anywhere. Do you have a plan for publication of this contents?

Explain STM

wait for publication by @vsts

In kindle format text isn't black

On kindle none part of text is totally black. It's dark grey. That makes reading not as comfortable as it could be.

```instance Time Int``` needs to be added in "Step 2: Adding Durations"

E. g.

instance Time Int where
    sec x     = SEC x
    minutes x = x.sec * 60
    h       x = x.sec * 3600

In "Enhancing the DSL for type safety", code sample "The full solution for durations in one go". Else 3.sec + 1.h - 30.minutes == 1803.sec won’t work.

Wrong function composition in "Designing with functions and composition"

The chapter contains two function compositions, which use the static function, that is also declared in this chapter.

The static function: static :: Board -> Double

The two usages:
valueTree = static . prunedTree
maxValue = maximize . static . prune 5 . gameTree

The usages are wrong, since static requires a Board (not a Tree of Board) and it returns a Double when maximize requires also a Tree.

The composition is correct in the linked example from the book (example):

evaluateBy :: Ord a => (Board -> a) -> Int -> Board -> a
evaluateBy f lookahead = minimize . fmap f . prune lookahead . gameTree

nowValue :: Int -> Board -> (Double, Board)
nowValue lookahead board = (evaluateBy static lookahead board, board)

Here static is used with fmap, which applies it on the values in the Tree of Board.

So the fixed chapter would contain:
valueTree = fmap static . prunedTree
maxValue = maximize . fmap static . prune 5 . gameTree
but probably also needs some explanation on fmap, when putting it there.

Examples using "!!" need to point out that importing Data.List is needed

!! was moved to Data.List. Proposal to add

import Data.List(!!)

to sample code.

Explain Simple Lenses

See issue 278

"class Millimeter (Integral a) => a" needs to be "class (Integral a) => Millimeter a"

Error in code titled "The definition of a Millimeter type class for an integral type "a"" in section "A mini DSL with type classes/Initial Implementation".

explain catch - finally and lambda capture

see
https://stackoverflow.com/questions/32959378/how-to-handle-exceptions-in-frege?noredirect=1&lq=1

also delve into exceptions as sum types in the native declarations

Wrong example in "Fun with Numbers"

https://dierk.gitbooks.io/fregegoodness/content/src/docs/asciidoc/what.html

Instead of
1 / (1 - 1/3 + 2/3) -- Infinity
it should be
1 / (1 - 1/3 - 2/3) -- Infinity