chrisdone

{-# LANGUAGE TypeOperators, LambdaCase, StandaloneDeriving, GADTs #-}

data Type env t where
  -- A constant type. Add kinds?
  -- Maybe, (), Int, Either, (->), etc.
  Constructor :: kind -> Type env kind
  -- A free variable.
  -- a
  FreeVariable :: kind -> Type env kind
  -- Type application.

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Template Haskell Quick Start

Use the template haskell (abbreviated to "TH") extension in a module with:

{-# LANGUAGE TemplateHaskell #-}

There are a few key pieces of syntax:

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-- | Load a renamed cell.
resolveRenamedCell ::
     Map Hash (Either LoadError LoadedExpression)
  -> FillerEnv LoadError
  -> IsRenamed (Expression Renamed)
  -> RIO DocumentReader (Either LoadError (IsResolved (Expression Resolved)))
resolveRenamedCell globalTypes globalHashes isRenamed = do
  hasConstraints <-
    pure $
    first LoadGenerateError $

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fineGrained :: Spec
fineGrained = do
  describe
    "Successful"
    (do it "a ~ a" (shouldReturn (unifyConstraints' [a .~ a]) (pure []))
        it
          "Integer ~ Integer"
          (shouldReturn (unifyConstraints' [_Integer .~ _Integer]) (pure []))
        it
          "a ~ b"

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{-# LANGUAGE DataKinds #-}

-- | My database API.

module DBAPI where

import Data.Defaults

data ConnSpec p = ConnSpec
  { username :: !(Required p String)

chrisdone

22-03-21 13:32:52.939 $ cat /opt/hindent-ormolu 
#!/bin/bash

/opt/ormolu-0.1.4.1 \
     "--ghc-opt" "-XBangPatterns" \
     "--ghc-opt" "-XNumericUnderscores" \
     "--ghc-opt" "-XOverloadedLabels" \
     "--ghc-opt" "-XPatternSynonyms" \
     "--ghc-opt" "-XTypeApplications" \
     "--mode" "stdout"

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Intro

I've been working on a parser for a Haskell-like syntax called Duet. In the implementation I've taken particular care to make an awesome tokenizer and parser that is super helpful to learners.

Jasper Van der Jeugt made a talk about producing good error messages recently, which coincides nicely with my parallel work on this. So I thought I'd also share my

chrisdone

{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE StandaloneDeriving #-}

-- | Print STG in GHC 8.4.3.

module Main where

import           Control.Monad.IO.Class (liftIO)
import qualified CorePrep

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Total (non-error-throwing) lambda-calculus evaluators.

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                               Appendix 2


                      Continued Fraction Arithmetic


                                  by