Safe Haskell	None
Language	GHC2021

Howl.Builtins.Context

Description

Builtins and helpers for working with evaluation contexts.

This module provides functions for parsing and evaluating input, defining rules with Set/SetDelayed semantics, and installing the standard context-related builtins.

Synopsis

data LHS
- = LHSSymbol Symbol
- | LHSPat Expr
- | LHSTaggedPat Symbol Expr
addContextBuiltins :: Eval ()
setDef :: LHS -> Expr -> Eval Expr
setDelayedDef :: LHS -> Expr -> Eval ()
run :: Text -> Eval Expr
run_ :: Text -> Eval ()
get :: FilePath -> Eval Expr
get_ :: FilePath -> Eval ()
evalWithHistory :: Expr -> Eval (Int, Expr)

Documentation

data LHS #

A left-hand side that can appear in Set or SetDelayed.

Constructors

LHSSymbol Symbol	A plain symbol left-hand side such as `x`.
LHSPat Expr	A pattern left-hand side such as `f[x_]`.
LHSTaggedPat Symbol Expr	A tagged pattern left-hand side such as `tag /: f[x_] := rhs`.

Instances

Instances details

Show LHS #
Instance details Defined in Howl.Builtins.Context Methods showsPrec :: Int -> LHS -> ShowS # show :: LHS -> String # showList :: [LHS] -> ShowS #
FromExpr LHS #
Instance details Defined in Howl.Builtins.Context Methods fromExpr :: Expr -> Maybe LHS #

addContextBuiltins :: Eval () #

Add the standard context-related builtins to the current context.

setDef :: LHS -> Expr -> Eval Expr #

Define a rule with Set semantics.

setDelayedDef :: LHS -> Expr -> Eval () #

Define a rule with SetDelayed semantics.

run :: Text -> Eval Expr #

Parse and evaluate an expression from Text.

run_ :: Text -> Eval () #

Parse and evaluate an expression from Text, discarding the result.

get :: FilePath -> Eval Expr #

Read, parse, and evaluate an expression from a file. The expression may be a compound expression, e.g. a sequence of semicolon-separated subexpressions.

get_ :: FilePath -> Eval () #

Read, parse, and evaluate an expression from a file, discarding the result.

evalWithHistory :: Expr -> Eval (Int, Expr) #

Evaluate an expression and record it in the In/Out history.