GitHub/gf-core
1
0
Fork 1
mirror of https://github.com/GrammaticalFramework/gf-core.git synced 2026-05-22 09:32:53 -06:00
Code Issues Packages Projects Releases Wiki Activity

Update LambdaCalculus.md

Browse Source
This commit is contained in:
Krasimir Angelov
2021-11-03 16:29:10 +01:00
committed by GitHub
parent 208998d1f9
commit eb3baa5c43
1 changed files with 10 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
doc/hackers-guide/LambdaCalculus.md
View File

@@ -14,16 +14,26 @@ We will start with the simplest possible subset of the GF language, also known a
```Haskell ```Haskell
data Term data Term
= Vr Ident -- e.g. variables: x,y,z ... = Vr Ident -- e.g. variables: x,y,z ...
| Cn Ident -- e.g. constructors: cons, nil, etc.
| App Term Term -- e.g. function application: @f x@ | App Term Term -- e.g. function application: @f x@
| Abs Ident Term -- e.g. \x -> t | Abs Ident Term -- e.g. \x -> t
``` ```
```Haskell
type Env = [(Ident,Value)]
data Value
= VApp Ident [Value]
| VClosure Env Term
```
```Haskell ```Haskell
eval env (Vr x) vs = apply (lookup x env) vs eval env (Vr x) vs = apply (lookup x env) vs
eval env (Cn c) vs = VApp c vs
eval env (App t1 t2) vs = eval env t1 (eval env t2 : vs) eval env (App t1 t2) vs = eval env t1 (eval env t2 : vs)
eval env (Abs b x t) [] = return (VClosure env (Abs b x t)) eval env (Abs b x t) [] = return (VClosure env (Abs b x t))
eval env (Abs b x t) (v:vs) = eval ((x,v):env) t vs eval env (Abs b x t) (v:vs) = eval ((x,v):env) t vs
apply (VApp c vs0) vs = VApp c (vs0++vs)
apply (VClosure env (Abs b x t)) (v:vs) = eval ((x,v):env) t vs apply (VClosure env (Abs b x t)) (v:vs) = eval ((x,v):env) t vs
``` ```