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small fixes to Lambda

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Philip Wadler 2019-01-09 11:12:23 +00:00
parent ad6f853946
commit 56ac5c007e
1 changed files with 3 additions and 3 deletions
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6
src/plfa/Lambda.lagda
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@ -464,7 +464,7 @@ Let's unpack the first three cases:
with `x`, the variable in the term. If they are the same,
we yield `V`, otherwise we yield `x` unchanged.
* For abstractions, we compare `w`, the variable we are substituting for,
* For abstractions, we compare `y`, the substituted variable,
with `x`, the variable bound in the abstraction. If they are the same,
we yield the abstraction unchanged, otherwise we subsititute inside the body.
@ -531,14 +531,14 @@ In an informal presentation of the operational semantics,
the rules for reduction of applications are written as follows:
L —→ L′
-------------- ξ-·₁
--------------- ξ-·₁
L · M —→ L′ · M
M —→ M′
-------------- ξ-·₂
V · M —→ V · M′
---------------------------- β-ƛ
----------------------------- β-ƛ
(ƛ x ⇒ N) · V —→ N [ x := V ]
The Agda version of the rules below will be similar, except that universal